What "market price" actually means, and why every site gives you a different one

If you look up the same card on four sites you will get four numbers, sometimes 40% apart. None of them is wrong. They are answering different questions. ## eBay: what people are asking Search results on eBay show active listings — what sellers hope to get. Asking prices skew high, because unrealistic listings sit there for months while realistic ones sell in a day. The longer a listing survives, the more it pollutes the average. Use it for: availability, and the ceiling of the range. Do not use it for: what your card is worth today. Sold listings are a much better signal, but eBay restricts programmatic access to completed-item data behind a separate approval tier — which is why most price tools quietly show you asking prices and call it market data. ## TCGplayer: what people paid TCGplayer's market price is derived from actual completed sales on their platform. For raw modern English cards it is the closest thing to a true transaction average that is publicly available. Use it for: raw near-mint modern singles. Weak on: graded cards, vintage, and anything with thin volume. ## PriceCharting: a curated index PriceCharting maintains its own index across sources with explicit graded tiers — raw, PSA 9, PSA 10 as distinct series. It is the cleanest single source for graded comparisons and for long time series. Use it for: graded cards and historical trends. Weak on: very recent releases, where its index lags. ## Regional marketplaces: a different market entirely Tradera in Sweden, Cardmarket across Europe. These are not just currency conversions of the US market. Local demand genuinely differs, and shipping and customs mean a card can sustain a real price gap between regions for years. ## How Cardex handles it We store every source separately, never blended into a single opaque number, and we show you the per-source average alongside a weighted blend. The weights reflect how close each source is to a real transaction: TCGplayer market price leads, PriceCharting follows, eBay asking prices are discounted, and auction-bid data from regional marketplaces is discounted further. Anything modelled rather than observed is labelled as an estimate. You should always be able to see which number came from where — a single "value" figure with no provenance is the thing this hobby has too much of already.