Mewtwo

This set's barely a fortnight old, so expect prices to keep falling for the next couple of months—that's the standard pattern once a Pokémon release hits the market. At £1.90 you're not looking at a locked-in floor, so there's no rush to buy or sell just yet if you're watching this one.

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