There are some people on this board with access to upcoming dealer auctions if you can go cash all in.

Also crazedlist dot org is a good metasearch resource. Some good cars that don't quite make cars com or autotrader can be picked up there.

Out in the open deals are few and far between. I saw an Aero Blue about 30k miles for 16k from a private seller but I didn't have my finance in place at the time. It went to a dealer who sold it for just under 19K.

Good luck.