and if it is stocked, its at ridiculous prices (amazon has it for 90 dollars as a standalone game. you srs right now?)
I've seen it vary from $40-90 on Amazon. As far as retail stores, it's quite a labor finding one. Used copies of Rock Band 2/Greed Day RB/etc. exist, but finding RB3 is a pain. I managed to get one for christmas, and it's been a blaze of glory since.