[husker boxster]

As a semi-Wheeler Dealer, I've found the sweet spot for pricing a private sale car is 1/2 way between Clean Trade-In and Clean Retail in NADA. Then you adjust accordingly up or down depending on additional features (like a transferable warranty) and condition.

Your car in my neck of the woods comes out at $28.1 using my formula. Your value will probably come out a bit lower b/c there are more Porsches for sale in SoCal. Your warranty probably adds $1K.

But...
You have a desirable year (b/c of the 9A1 engine), model (S), color, and a very low production volume due to the recession. Supply and demand - for one of the few times in life you have both working in your favor. Why not start at $30K (or $29,950) and see how much interest you get? My dad liked to say "you can always come down in price, but you can't go up".