Used cars in orange county (online listings)

My aunt lives in Orange County and she is looking for a used car. Where can I find online listings of used cars for someone who doesn't have a ton of money?

Hmmm.... my favorite place for online classifieds is craigslist, but you could also go through the autotrader. Honestly I would look more through both of them as well as kelley blue book and any other car resource before purchasing a vehicle. Make sure to have a mechanic inspect it first to make sure you are getting a good deal.