I picked up Def Jam Rapstar w/ USB mic (Logitech) for $3.00 at Walmart last night for Xbox 360. I didn't think about CAG till I got home and then wished I had picked up the remaining 4 or so copies. If anyone would like, I have no problem going back and buying up the rest of them for anyone here that wants them. I will add that the cardboard boxes all have some sort of damage. None of the boxes were mint. The game and mic inside of mine were flawless. I don't know what shipping would cost, I'm sure the mic will add a little bit of weight. Either way, I'm guessing the whole thing could be bought and shipped to you for around $10.00.
If this is anything you are interested in let me know, and I'll pick up the rest of them. I think there was around 4 left.