if you scratched your fairings and went through icbc, that itself can give it a rebuilt status, but thats just aesthetic damage. bike should run just fine.
on the other extreme end, forks and/or engine and what not could have been damaged from a crash before to give it a rebuilt status as well. just buyer beware and always get a pre-inspection and carfax (or other similar car reports) done.
tegz, yea, i just started my bike, seems idle is around 1200-1400rpm. was just taking an eyeball guess on top of my head for that 3k rpm guess :P
on the other hand, this doesn't seem so bad of a deal:
2009 Kawasaki Ninja 250r SE *Mint* $4000