Comparable sales, defined

A "comp" is a completed, realized sale of the same card in the same grade — same year, set, player or character, number, grader, and grade. It is what someone actually paid, not what someone is asking.

Why asking prices do not count

Listings and "for sale" prices are aspirations; only closed sales reflect real demand. Good valuation ignores the noise of asking prices and outliers and focuses on the cluster of recent realized sales.

More comps, tighter value

A card that trades often has many comps and a confident, narrow value; a rare card has few and a wider range. Slabline aggregates comps and shows sales volume alongside the value, so you know how much to trust the number.