This deal has ended.
Best Buy again has Rock Band 2 for either PlayStation 3, XBox 360, or Nintendo Wii on sale for just $19.99. This is just the gaming software and does not include any of the instrument controllers. The Wii version is backordered and will ship within one to two weeks. Shipping adds $2.99, in-store pickup is free where available, and sales tax is charged in most states.