Rode on the back of a CBR 900RR to 130 mph!

[929PhoenixSquid]

Unfortunately, there is really no way to tell whether a bike has been dogged or not. Many people will tell you to inspect the bike for road rash, but you might pass up a mechanically incredible bike in for a perfect "looking" bike that's never had the oil changed or been tuned up for years.

I would highly recommend a 600cc sportbike from 1999-2001. 600's lose their value quicker than 750's or liter bikes. As far as models are concerned, look into the following:
Honda CBR600F4
Kawaksai ZX-6R
Yamaha R6
Suzuki GSXR-600

Try to find a bike completely stock with 2,000-7,000 miles on her. Aftermarket exhausts can cause the valves to burn out prematurely if the bike was not setup properly. They come out of the factory lean, so adding a less restricive exhaust makes them ever MORE lean. They would have to install a jet kit and have the carbs professionally synced in order to pull that off without damaging the longevity of the bike. Besides, the more mods that have been done, the more potential problems you may have to deal with.