tip and scan to Joystiq of their pricing for Harmonix's Rock Band peripherals for both the PS3 and Xbox 360. The microphone and drum kit cost $29.99 and $79.99, respectively. Unfortunately, the guitar controller has a price discrepancy between the two platforms, with the PS3's wireless guitar costing $59.99 and the 360's $79.99, a twenty dollar difference.
As the story goes, Red Octane supposedly couldn't get a wireless guitar because using Microsoft's proprietary wireless technology would jack the price on the controller. Could the PS3's wireless technology be easier and cheaper to implement that would cause it to be cheaper than the 360's? Harmonix denied their being any discrepancy when asked that question, so we'll have to wait for either an announcement on pricing or some more concrete evidence from retailers.