+208%
Across 12 PSA 10s with 25 or fewer graded copies, the middle change over 6 months was +208%. Half fell between +45% and +370%.
PSA 10s from the same sets with more than 100 copies: +121% (25 cards; half between +76% and +167%).
Wizards and e-Reader cards (1999 to 2003). Each card needs a sale in the last 6 months and one in the 6 months before. Prices as paid. Updated Oct 18.
Scope: PSA 10 grades with a PSA population of 25 or fewer (the latest count we verified) on Wizards of the Coast cards, the e-Reader sets Expedition, Aquapolis and Skyridge included. A grade counts when it has at least one sale we counted in the last 6 months and one in the 6 months before. Its change is the median price paid in the last 6 months over the median of the 6 months before, minus 1. The comparison group is the same sets' PSA 10s with a population above 100. Population counts exist for the cards we track, so the group is small; one or two sales can move a grade a long way.