Ha, JTP beat me to it - but here goes anyway......
Art - you are still only seeng the top of the iceberg.
Have you factored in the upcoming maintenance and insurance costs? If you are good with the spanners, you can save heaps of $$, but if you have to take the car to a shop, you had best be prepared for some significant bills. Its a certain fact that ALL cars need maintenance, repairs and the replacement of mundane parts like brake pads, rotors, air / cabin filters, spark plugs etc etc.
Boxsters are no exception, with known weaknesses like AOS failure, MAF replacement and plug coils high on the list - and these can bite without any prior warning to the owner. The other problem to consider is that some these parts can be expensive to buy and doubly so if you have to get a shop to install them....
As a general rule of thumb, I always put aside 10% of the purchase price for unknowns......