I didn't realize just exactly how many I've obtained. 52 is the total count, with 14 Pikachu (including the little Pika-butt keychain above AngryChu's head).
I've legit bought all of these in person at stores like Target, GameStop, Barnes & Noble, Wal-Mart, a couple local anime stores, and at anime cons. Mostly at Target and GameStop, though.