I just have to weigh in on this S Box versus non. First off think about what you want it for.
-Are you going to track it, autocross etc? Different classifications for engine size tracking etc.
-An S would be harder to rein in meaning that you have speed limits that can be more easily reached in an S at a faster rate. How much power do you need? For example in terms of fun it is more fun to drive a Miata in a lower speed environment because it is harder to exceed the speed limits and you can rev the engine like crazy. On the same principle that is why I have a 2001 Box base. It would get better mpg than an S and has sufficient power for me. However as the above says an S would have better resale.
Higher mileage examples means more wear and tear. I bought my Box with 30k miles and now has 40k miles. So I have not replaced much of anything. I have added the IMS Guardian, had the CV joints done, new accessory belt, tires, coolant change etc.
Read the thread on this forum 'thinking of buying a Boxster'.
What options do you want? Manual trans. or tiptronic?
Heated seats? etc etc
Ask for receipts for work done/parts purchased.
Dont buy the first one you look at. Try several different cars. Do not be in a hurry.
Get a PPI done on the one you like(indy shop did mine). Watch out for this. Before you start the car, turn the key on without starting the engine and make sure all warning lights light up especially the CEL one. On starting the engine make sure all these lights go off. Basic stuff. Oil leaks are not good. Make sure convert. top goes up and down and the air. cond. works.
Patience is key. Do lots of reading on this forum. Knowledge = $$$$$ saved.
Cheers, Guy.
And yes it is the most fun car I have owned.