[Perfectlap]

I paid $140 for a diagnostic from Ray Catena in Edison,NJ. Its the top dealer here in NJ. You should offer to pay the seller to take it there for an inspection and have him send you the print out. Important to check is the clutch, suspension, brake wear, etc. I'm assuming the car is close to central NJ however.
I had the car towed to another Porsche dealer in Parsipanny I think, Paul Miller Porsche, for some work. I was too busy to drive it in. Unfortunately that's still the case these days!
Another thing, the diagnositc is a great bargaining chip. If they find it needs x dollars of work you can use that to haggle for a lower price. At 47K miles its 10K miles short of the big maintenance jobs mentioned above.