Do your homework. Pick some criteria and see what dealers around the country are asking.
You could also check KBB and even blackbook if you have access to a dealer you know personally. Once you have it figured out what you want and near what you should pay, find a few local dealers.
Thoroughly inspect the car and obviously ask for a carfax or report on its history. Test drive, make an offer, and hopefully you'll find something you like. Good luck.
2009 Chevrolet Corvette