The “real” drum kit for RB2 (which also works with RB1 and it’s rumored to work with GH4 also) is a little spendy: It’s $300. As promised, it can also be hooked up to a “drum brain” to turn it into a real, full
electronic drum kit. The brain costs an additional $350.
For me, for now, I’ll stick with the default RB drum kit that I already have. But if I start really getting into drumming (or if Brett does), $650 is actually about the price of a “normal” electronic drum kit.
https://www.drumrocker.com/products/faqs.php