Pikachu

This is a fresh set—only two weeks old—and prices typically fall for the first three months after release, so there's no rush to buy in at £4.44 if you're holding stock. That said, early movers do occasionally catch a spike before the market settles, though betting on that with a Pikachu is a mug's game.

• CautionSet is 2 weeks old. Prices typically fall for the first three months after release.