I suppose I may be a little late to chime in, but I would wait and buy new, saving the few extra bucks for the hyper would probably be worth it. I bought a buggy that looked like it was in good shape (used) on e-bay.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5959880687&rd=1&sspagename=STRK:MEWN:IT&rd=1
The total I paid was $330.00 (I think 370.00 with shipping and the money order charge). To date I am up to 900 dollars on this car, and I have only ran 3 tanks through it. It needed (or at least could use), a wing, body, wheels, steering servo, tranny cases (swaybar mounts crushed from impacts), swaybars (both of the previous are supposed to come with a 9.5 pro), shock rebuilds, one front shock body, new wheels (current ones had such a small recess that you could not use a wrench to remove -- needle nose are not good tools), air filter, fuel line, gas tank (hole melted in it), front steering knuckles, brake linkage, a new right rear CVD, radio batteries, charger for glitch pack, battery for glow starter, glow plugs, a carbueretor boot, temp gauge, and fuel.
Obviously, not all used cars will require this, but it is just alot safer to get a car that has not had anyone else crash it into stuff. But after all of the above, I still can't clear the 40 footer that my buddy can with his stock Hyper.