Methodology

Most One Piece TCG pricing you will find online is published by someone who wants to sell you the card, or by a content site rewriting last month's numbers. Both have a reason to be optimistic. We do not.

Foilr runs a separate storefront, the Foilr Shop, for stock we own ourselves. It is always labelled as ours and it is never weighted in any signal, ranking, or board. A card we happen to hold gets exactly the same treatment as one we do not.

Foilr is an independent, fan-run product operated by Studio PowerUp LLC. It is not affiliated with, endorsed by, or licensed by Bandai or the ONE PIECE Card Game. Card names and images identify the products we track; all trademarks belong to their owners.

Every card price on Foilr is a market observation — a record of what a market actually did — not our estimate of what a card is worth.

• English / US market: TCGCSV, a bulk feed derived from TCGplayer market data. Pulled once per day. This is the number shown as the market value on a card page.
• Japanese market: Yuyutei. Pulled once per day and converted to USD.

We keep the full daily history rather than only the latest value, which is what makes the price charts and the movement boards possible. A price you see on a card page is the most recent observation from that source, not a blend of several.

Both markets are reported in USD. The Japanese figure is a conversion of a JPY price and will move with the exchange rate as well as with the card.

Graded prices are sourced from PriceCharting, which builds them from completed eBay sales rather than asking prices. A completed sale is a far better signal than a listing, because anyone can list a card at any price.

We ingest seven grade tiers per card where they exist — raw, PSA 9, PSA 9.5, PSA 10, BGS 10, CGC 10, SGC 10 — plus the sales volume behind them. Volume matters: a “PSA 10 price” drawn from two sales is not the same claim as one drawn from two hundred.

One known wrinkle we correct for: a graded source's idea of a card's raw price often refers to a different printing than the one we display. Where the two disagree, we use the live market raw that the card page itself shows, so the raw price and the graded price on the same screen always refer to the same card.

The grading blogs in this space publish rules of thumb. Here is the actual arithmetic, so you can disagree with it.

Expected value of submitting a card is a weighted blend of the likely outcomes:

EV = (0.30 × PSA 10) + (0.55 × PSA 9) + (0.15 × raw)

The weighting is deliberately pessimistic: it assumes a PSA 9 is the most likely result, not a 10. Foil surfaces on high-end One Piece cards scratch easily and genuine 10s are scarce, so an optimistic model would be a misleading one.

Grading costis applied as a tier based on the card's raw value, reflecting how the graders actually price their service:

• raw under $200 → $45
• raw $200 to $500 → $75
• raw $500 to $1,000 → $135
• raw above $1,000 → $235

Expected gain is then EV − raw − grading cost. A card is only shown if that clears $25, and if it passes every one of these gates:

• raw price is at least $15 (below that, fees swamp any upside)
• the PSA 9 price is at least the raw price, and the PSA 10 price is at least the PSA 9 price — if not, the data is inconsistent and we do not use it
• at least 30 recorded sales behind the numbers
• the PSA 9 is not more than 5× the raw, and the PSA 10 not more than 10× — a ratio beyond that almost always means the source is comparing two different printings, not describing a real premium

This is an estimate of expected value, not a prediction. It cannot see the condition of your specific copy, which is the single biggest variable in whether a submission pays.

• Every 30 minutes: official One Piece news (banlists, errata, promos, expansions) and curated retailer restock checks.
• Hourly: the official products page, for release-calendar changes and new-product reveals.
• Daily: English card prices, Japanese card prices, sealed-product prices, graded values, the derived price-movement signals, and the organised-play event calendar.

Each of these runs as a monitored job. When one fails or goes quiet it raises an internal alert rather than silently serving stale numbers — a price that stopped updating is worse than no price, because it looks current.

This is a deliberate design rule and it costs us coverage. When a derived figure fails its sanity checks — inconsistent grade ordering, too few sales behind it, a ratio that implies the source is describing a different printing — we do not show it with an asterisk. We show nothing.

The reasoning: people skim. A caveat under a number is read far less often than the number above it, so a hedged figure is functionally an unhedged one. If we are not confident enough to let a figure stand on its own, we are not confident enough to publish it.

The practical consequence is that some cards show no grading estimate and some show no Japanese price. That is the system working, not a gap.

To be explicit about the boundaries:

• Not an appraisal. Our prices are market observations. They are not a valuation of your specific copy, whose condition we cannot see.
• Not investment advice. We are not licensed advisors. Collectibles are illiquid, volatile, and can lose most of their value on a single reprint announcement.
• Not a prediction. A rising price is a description of the past. Our movement boards say what moved, not what will.
• Not complete. We cover what our sources cover. A card with no recorded sales has no price here, and that is not the same as it being worthless.

If you are quoting a Foilr figure in an article, a video, or an answer, please link the specific card or board page it came from rather than the site as a whole, and include the date you read it. An undated price from us will be wrong within a week, and we would rather be cited accurately than often.

Card page URLs are keyed to the printed serial and are stable: https://foilr.gg/card/OP05-119 will always be that card.

Found a number that looks wrong? Every card and board page has a report link, or email hi@foilr.gg. Corrections are the cheapest trust we can buy.