Amazon has Lego Rock Band for XBox 360 marked down to just $7.93! That is 74% off of the regular price of $29.99! You can also get the Wii version for only $10.66, or the Playstation 3 version for $11.49. This game also has a 4.5 out of 5 star customer rating.
Please keep mind mind that Amazon prices can change very quickly!
(Thanks Common Sense with Money!)