Well im trying to get an idea of how much it will cost me... But i found a really basic frame with wheels and a seat (the one in the link) I wish I could find something exactly like what you have that would be perfect.. But im going real cheap for now, i just want something fun and fast enough to keep me awake lol..
heres the one im looking at. I'm gonna ask him if he'll take $75 without the motors.
http://stillwater.craigslist.org/for/1780104741.html
Its fat enough to put an engine next to the driver and i think fat/low enough not to flip unless i really hammer into a turn