it will cost like 11$ for whole album or so,
You buy the rockband game and then create account on Microsoft Market or Playstation Store and then you can buy card to add funds to your account or use credit card.
I have PS3 because games I am interested are far more superior or that, and it comes with BlueRay, but Xbox 360 is also tons of fun and is cheaper , but you must buy version with HDD.