Check these guys out:
http://www.expomc.com/
I bought mine from them and they do a killer business nationwide with quality cars at good prices. They list all their stuff on eBay, but you can call them and deal directly. They'll bring it to the local Porsche dealership for an inspection for you, too. They'll sell a Boxster for about $500 (possibly more) less than their "buy it now" price. It was a great buying experience and I'll look there again any time I buy a car. They have good high end inventory and new stuff comes in all the time. I've been to their dealership in Houston and it's a legit place.