I have found a good selection of used cars at both Thorstad (S. Park St.) and at the lot on the SW corner of Fish Hat/Beltline (Zimbrick, I think). Both are dealerships and have a long term stake in keeping their reputations clean.
However, two things:
-- I agree with the comment about buying from an individual, checking the records, and getting an independent inspection. You're cutting out the middle man and saving a few dollars, if you are willing to do the work. That's the tradeoff.
-- What you're looking for is the right VEHICLE, and wherever you find it is the right place. Cast a wide net, take your time, do your research. Get the loan lined up ahead of time if you are serious.