I bought a 2006 Lexus GS430 from www.nashauto.com 4 weeks ago. Paid about $31,000 for car with 27k miles on it.
They're an independent dealer and they go to the same auctions that Official Lexus dealers go to get their used cars.
I visited multiple Lexus dealers - Cerritos, Beverly Hills, Newport Beach, Westminster.
All in all, these guys get their used cars from the same source.
It took me 3 weeks to buy because I'm a very thoughtful person when spending big money.
I ended up buying from Nash Auto, because their prices were lower than all the dealers by 5k-10k.
I think only Westminster could match the price but that was on a car that had 68k miles on it.
The salespeople were pretty low pressure. There's only 2 or 3 of them. To test drive the cars, they photocopied my license and let me drive off on my own. I didn't have someone talking in my ear as I was trying to evaluate the car.
In the end, I saved a LOT of money and I think the vehicles are equal quality to the ones you'd find at the official Lexus lots.
I was acctually put off my the Newport Beach Lexus btw - the salesman I was talking to there lied about the car I was looking at. Claimed that it was completely local, when car fax clearly showed it was mostly driven in Colorado!!!!
Anyways, give them a look if you're interested.