Source for inexpensive AG5 (398A) button cells?

[Turbo DV8]

I just scored two Eddie Bauer "Nano Tac" keychain lights for $2.64 each on clearance at Target. They use four AG5 (398A) button cells

but the thing's just cute enough that for $2.64, why not? I've seen a big card of some larger button cells at Target for pretty cheap, but not AG5. Anybody know an inexpensive source for these cells? (Preferably a B&M store.)