I'm currently running an 80mm 2000KV Medusa with a 16T pinion on 4s lipo and it performs well but the motor runs hot. If you're looking for a cheap motor I'd look for 1100-1300 KV 80mm Medusa and run it on 6s lipo (14-15T pinion should do fine). I'm waiting for the new CC Neu motors to come out and I'll be replacing my Medusa with one of them. Neu 1515 2.5D or 1.5Y on 6s will do well, I ran it on a 1515 1.5D with a 13T pinion at first and it ran really well but the motor was a bit hot. A 1521 produces mad power on 6s lipo, a 1521 1Y on 6s lipo is going to take some throttle control to keep it on the ground:
http://www.youtube.com/watch?v=bo7GdkNpKAY