Bruce is right about not buying a Porsche before you personally drive it. I could have easily found the transmission problem I now have by driving it first... and I'd have negotiated it off the price or passed it up quite thankfully, even though it was expensive to go there and drive it.
If you're going to plop down $30k of your hard earned money, is it not worth $600 (airline ticket, a night in a motel if necessary, and a mechanic's inspection) or so to fly to wherever the car is located and drive it to a mechanic for a checkout?
One trip to the repair shop will cost you more than this. I speak from experience
PS - Buy an S if at all possible! Wish I had the cash to do it, but I did not.