bought mine secondhand off yahoo auctions for $80 delivered. Chucked it on my N/A RB20DE with a "race pipe" (no need to worry about ceramic turbines) and scared the ba-jeezus out of everyone when the clutch got dumped.
It now resides on a CA18DET in an actual race car, so its sorta well suited. Which reminds me, there's different Rev Limiters for different engines, RB and CA are the same though.
If you hook the handbrake signal cable up, then you can dial in 2 different max RPM's before cutting ignition. Really good for drag racing, sorta pointless on the track.