Gotham City Impostors is loads of fun. Hard Corps: Uprising is another fun, although challenging, game to play, too. Actually.. You should head on over to the Indie section and check out EZMuze Hamst3r Edition. I can't remember how much it was (400MSP??)
but it's easily the best Indie game ever made. It's a music creation game and for what it is, it's really good when you start figuring out techniques.