If you are wiling to take a drive I know where there are a ton of them. SC, AL, IN, WIS. They Start at 18k cheepest with low miles is 15k. If you wanna drive and be comfortable and have the power get the LS1/LS2.
Joe Van Horn Chevrolet in Wisconsin has like 3 under 18k with like 23k miles. http://www.vanhornchev.com