eBay

eBay is the deepest secondary market for Pokémon cards in the world — practically anything, from bulk commons to six-figure graded vintage, trades here.

It runs both timed auctions and fixed-price (Buy It Now) listings, so it sets the de-facto market price for most cards. Buyer protection covers most purchases, but because listings are seller-written free text, it pays to check photos, grading labels, and seller feedback carefully.