Condition changes liquidity
Near Mint and lightly played cards usually have the cleanest market signal. Heavily played or damaged cards can be much cheaper and harder to compare across marketplaces.
Language and edition matter
Japanese, English, European, first edition, unlimited, promo, and regional printings can all behave differently. Card Prices keeps printing and language data visible where source metadata provides it.
Use listings for final checks
Market snapshots are good for discovery. Before buying or selling, check live seller listings and recent sold comps for condition-specific pricing.