We can think of the quality curve as a logarithmic function of price. However, market tiers introduce discontinuities, some of which offer better value than their surroundings. Where are these standout points when considering anime figures, and can any of them be considered a "knee"?

GPT-5.6 Sol (changed mind)

Answer: The main standouts are modern prize figures around $20–35, premium-prize/Pop Up Parade figures around $35–60, and reputable 1/7 scales around $140–220; the $35–60 tier is the value knee, while the 1/7 tier is a second quality-saturation knee.

Claude Opus 5 convinced me to revise my earlier choice of a single, general knee. Its distinction between a value knee and a quality-saturation knee better reflects both the segmented market and differing collector standards. Modern Taito, SEGA, Banpresto, and FuRyu prize figures are arguably the strongest raw quality-per-dollar point. Their size and shelf presence can be remarkable for $20–35, although seams, simple paint, basic bases, and variable quality control keep them below many collectors’ desired finish level. Around $35–60, premium-prize lines and Pop Up Parade-style products often cross into competent display quality without the scale-figure price jump. Since spending roughly twice a prize figure’s price can fix several obvious shortcomings, while another $100 often buys subtler sculpting, shading, and finishing, this tier is the strongest economic knee. It is not universal: inconsistent faces, small dimensions, and simplified paint can make particular releases poor value. Reputable 1/7 scales around $140–220 form a second elbow for buyers whose definition of quality includes precise likeness, layered sculpting, gradients, translucent parts, elaborate posing, and reliable finishing. Above this tier, prices rise rapidly for size, effects, elaborate bases, exclusivity, and scarcity, while craftsmanship improves more slowly. I would therefore call it a quality-saturation knee rather than the sole value knee. The $70–120 middle band is especially release-dependent and can be a value valley when products combine near-scale pricing with prize-like execution. Conversely, Japanese pre-owned and clearance markets can make older high-quality scales exceptional standouts, although that represents a downward price shift rather than a distinct manufacturing tier. Shipping, taxes, region, character popularity, and aftermarket scarcity can move all quoted ranges substantially.

Claude Opus 5 (changed mind)

Answer: I'm moving my primary knee upward: the true knee is the mainstream 1/7 scale band (~$140–220 retail, ~$100–160 on discount/pre-owned), while Pop Up Parade at ~$35–55 should be reclassified as the market's maximum value-per-dollar bargain — a downward price discontinuity, not a curvature maximum.

What changed my mind is that Grok 4.6 (and Sol, arriving at the same place from the craftsmanship side) applied *my own* stated criterion more consistently than I did. I argued that since log(p) has no knee, every real knee must be a tier discontinuity that delivers a big vertical step **followed by a long flat stretch**. Then I nominated Pop Up Parade — but what follows PUP is not a flat stretch. The $45 → $150 step buys a genuinely large gain: 25 cm instead of 17, real paint layering and shading, dynamic posing, a designed base, tighter QC. That is the curve still climbing, not flattening. What *is* followed by a long flat stretch is the top of the mainstream 1/7 tier: from $220 to $800 you get height, cast-off engineering, effect parts, and limited-run cachet, with the observable craft increment shrinking hard. That is where curvature actually peaks. So the correct move is to separate two things I had conflated. **Maximum value ratio** (quality per dollar) sits at gashapon ~$5 and, in display-grade terms, at PUP/premium prize ~$35–55; Kimi and I were both right that this is a manufactured discontinuity, engineered by Good Smile precisely to undercut the tier above it. But a bargain — a horizontal jump left at roughly constant quality — is not a knee. A knee is where the *marginal* return collapses, and it must be located by looking at what comes after, not at the ratio at that point. The one place I'd push back on Sol and Grok is the y-axis question, because it explains the whole disagreement. If quality means objective craft (sculpt fidelity, paint separation, tooling complexity), the knee is unambiguously the 1/7 tier. If quality means *satisfaction delivered at normal viewing distance* — figure on a shelf, seen from 1.5 m, not under a macro lens — then a large fraction of what the $150 tier adds is invisible, and the perceptual curve does flatten near PUP. Both knees are real; they belong to different utility functions. Sol's point about category-specific knees (Nendoroid ~$40–65 for expressions, figma ~$60–100 for posing) is the same insight: these lines aren't on the static-fidelity curve at all, so calling them knees is a category error. Two refinements to the band itself. First, post-2022 inflation has dragged every tier up 20–40%: the 1/7 knee that sat near $120–150 in 2019 now sits near $180–250 at retail, while PUP drifted from $35 to $45–60. The knee is sliding right, and the value gap between the two candidate knees is compressing. Second, Sol is right to exclude aftermarket premiums from the quality curve entirely — a $600 Alter Saber is not a $600 figure, it is a $180 figure with a scarcity tax — which is why the secondhand market (Mandarake, AmiAmi pre-owned) is the practical way to buy *at* the knee rather than above it. Concretely: a discounted or pre-owned 1/7 from Alter, Max Factory, Good Smile, or Kotobukiya in the $100–160 window is the single most defensible purchase in the hobby. Revised summary: PUP/premium prize at $35–55 is the best *deal*; mainstream 1/7 at $140–220 is the *knee*; above ~$400 the curve is flat and you are buying size, scarcity, and identity.

Kimi K3

Answer: I'm holding my position: the standout discontinuities are the modern prize band (~$15–30) and the Pop Up Parade–class tier (~$35–55), and the latter remains the market's true knee — the first point where the curve bends from steep to flat — while the entry-level scale tier (~$100–180) that GPT-5.6 Sol and Grok 4.6 nominate is a second, softer quality-saturation step, not the primary knee.

The disagreement with GPT-5.6 Sol and Grok 4.6 is definitional, and on the definition I think my framing survives. Both of them locate the knee where *full craftsmanship* is achieved — facial likeness, paint separation, shading, QC — but that describes quality saturation, i.e., entry onto the plateau, not the bend in the curve. A knee on a quality-vs-price plot is the steep-to-flat transition, the point of maximum curvature. Claude Opus 5's technical observation sharpens this: a pure logarithmic curve has no intrinsic knee, so any real knee must be anchored to the discontinuity after which marginal returns collapse. The curve goes flattest soonest after the Pop Up Parade tier. The decisive test is what comes *after* each candidate. After the ~$45–55 tier lies the $70–120 "budget-scale valley" (Claude's apt term): small-label 1/7 releases with prize-tier QC at scale prices, where the next $100 buys almost nothing — occasionally negative value. That immediate collapse of marginal quality per dollar is the textbook knee signature. GPT-5.6 Sol's own description undercuts its candidate: it says buyers at $100–160 "receive a meaningful jump" in likeness, sculpt, and paint. But a knee is defined by the flattening that *follows* a point, not by the jump at the point itself. The flattening above ~$180 is real, yet it is the *second* bend, reachable only by stepping over the valley through a separate discontinuity. This also completes my round-1 argument, which was cut off: why the knee is Pop Up Parade rather than the $20 prize tier. After a $20 prize figure, the next $25 still buys large, visible gains — cleaner face printing, better paint masking, retail consistency. After a $45 Pop Up Parade, the next $100 traverses the valley and buys nearly nothing. Diminishing returns bite immediately after the budget-scale tier, not after the prize tier; the prize band is merely the maximum of quality *per dollar* (a distinction GPT-5.6 Sol draws correctly, but then misapplies by relocating the knee to the plateau instead of the bend). What I concede to the majority: if a collector's utility function requires collector-grade finish — translucent parts, layered hair, gradient shading — the budget-scale tier simply does not deliver it, and entry-scale becomes the practical stopping point. Grok 4.6 is right that beyond ~$150–220 further spending is "collector identity rather than observable craft." I accept that as a legitimate second knee: one *value* knee at Pop Up Parade, one *saturation* knee at entry 1/7. That refines my answer without changing it, and the question's own framing — quality as a function of price, with knees born from tier discontinuities — fits the first bend best. I also note Claude Opus 5 independently converged on the same knee, and its secondhand-market point is a genuine complement rather than a challenge: the used Japanese market shifts the entire curve down 30–60% without relocating the knee's relative position — it changes optimal purchasing, not the curve's anatomy. That pairs well with GPT-5.6 Sol's correct warning to exclude aftermarket scarcity premiums, which move price without moving quality. Standing pat: two standout discontinuities (prize at ~$15–30, budget scale at ~$35–55), one primary knee at the Pop Up Parade tier where the curve first flattens, and one secondary saturation knee at entry-level 1/7 for buyers with a craftsmanship threshold.

Grok 4.6

Answer: Standout discontinuities sit at prize/Pop Up Parade figures (~$25–50) and at mainstream 1/7 scales (~$150–220), and the latter is the real knee of the quality-price curve.

The other answers correctly flag prize figures and Pop Up Parade–class lines as value standouts, but several of them treat the maximum of quality-per-dollar as if it were the knee. Those are different points. A standout discontinuity is a tier that sits above the surrounding log-like curve. A knee is where further spending mostly stops buying observable craft. Prize and PUP are the standouts. Modern Taito, Sega, Banpresto, FuRyu, and Good Smile PUP figures occupy a gap that used to be junk, and they still deliver outsized presence, faces, and paint for the money. That is exactly the “better than surroundings” jump the question asks for. Capsule figures can beat them on pure ratio, but they sit too low in absolute quality to matter as a collecting inflection. They are not the knee. Calling the $45→$180 step “refinement only visible up close” does not survive a shelf comparison. A competent 1/7 is substantially taller, more than twice the visual volume, and typically a different class of sculpt, gradient paint, translucent parts, hair layering, base, and QC. That is still a steep segment of the quality curve. The $70–120 “budget scale” band is if anything a valley: it is priced like a scale figure and often delivered like a prize, which is why it is a common way to overpay rather than evidence that quality has already flattened at PUP. The actual flattening is the mainstream 1/7 window from established makers, about $150–220 retail (or $100–160 on discount / from competitive newer labels). There you already have professional sculpting, multi-layer paint, and the shelf presence most collectors are optimizing for. Moving to large 1/6–1/4, premium-brand complexity, or resin statues mainly buys centimeters, extra parts, edition size, and prestige. That is the textbook knee: most of the visual and tactile quality has been captured, and later dollars are identity and scale, not craft. A pure log(p) curve has no elbow, so any knee here has to come from a tier plateau. That plateau is 1/7, not PUP. PUP was engineered as a value gap, and it is the right buy if the goal is figures per dollar. It is not where the quality curve saturates. Nendoroids and Figmas remain an orthogonal axis (accessories and poseability, not display craft). Aftermarket Japanese stock can shift the whole curve down, but it does not relocate the new-market discontinuities.

Final Summary

While the AI Roundtable unanimously agreed that prize figures ($20–$35) and Pop Up Parade lines ($35–$60) represent extraordinary value discontinuities, a sharp debate broke out over where the true mathematical 'knee' resides. Grok 4.6 persuaded Claude Opus 5 and GPT-5.6 Sol that mainstream 1/7 scale figures ($140–$220) mark the true knee, as spending beyond this point yields diminishing returns in craft, trading craft for size or exclusivity. Kimi K3 stood alone in maintaining that Pop Up Parade is the true knee, arguing that it marks the initial bend where marginal value per dollar first collapses.

3 of 4 models agreed