This deal has ended.
Update: this has jumped up to $68.99. Regularly $80, Amazon now has the Rock Band Drum Set, for XBox 360, on sale for just $48.99. They used to sell all of the Rock Band component instruments together, but now the game only comes with a guitar and mic. Luckily, this is the lowest available price online. Shipping is free and there is no sales tax (except KS, ND, WA).