KueMan10
CAGiversary!
It looks like it's sold at the same price for the 360 as well, but it is sold by a 3rd party and charges $10 shipping.
http://www.amazon.com/Rock-Band-2-Standalone-Drums-Playstation/dp/B001BXAC6W
http://www.amazon.com/Rock-Band-2-Standalone-Drums-Playstation/dp/B001BXAC6W