According to a memo that has shown up at Game Crazy that shows us the potential prices for the Rock Band peripherals.
The prices are just a little high in my opinion, I would hope that for we wouldn't be expected to pay an extra $50 for the game itself. What is interesting though is that the guitar is showing to be $20 more on the Xbox 360 than the PS3. Perhaps Microsoft opened up their proprietary wireless standard like they did for Guitar Hero III, which would account for the extra cost.
I did check in with my contact at Harmonix which assured me that they still have not decided on the pricing, let alone released it to retailers. Please take this info with the recommended dose of salt.
Memo shows $20 gap in Xbox and PS3 Rock Band guitar [via joystiq]