by kkps » Tue Sep 01, 2009 10:35 pm
Rock Band 2 has some added features (any character you create can play any instrument, for example), but in general the games are very, very similar. I would try Wal Mart I suppose, or any lesser-known game shops that might have some copies in stock.
To answer your other question, PS3 and PS2 would have different instruments.