First, here's the keyboard controller.
I have to admit, as a fan of synth music in the New Wave 80's, I was never crazy about the "guitarization" of the keyboard. You'll need $80 to get it, or bundled with RB3 for $130.
There's a three cymbal expansion kit also coming from Mad Catz. When you play in Pro mode, they become your hat, crash, and ride. I'm guessing this turns the regular pads into snare and toms. Not interested. They say they are reengineered to be quieter, but that leaves the question of the flimsy rubber membrane they sit on that tears after a few hours of mashing. For $40, I don't think they've fixed them.
Here's the $150 Fender that also works as a MIDI guitar.
And, finally, for those of us with MIDI outputs on gear already, here's this little doohickey...
It's a MIDI adapter. Also has a velocity sensitive adjustment to reduce crosstalk on your electronic drum kit. $40.
Grand total for the game and all new peripherals? $360.
I love Rock Band, but not THAT much! The MIDI adapter and my own keyboard is more than enough for me.