just go to eBay. My impression is $6k for a 2.7 or 3.2 with less than 60k miles as the going rate.
Consider you always hear complaints from the people with problems, those of us who have had no problems (2 Boxsters, 5+ years, trivial unscheduled maintenance costs) don't post. This is true for any item or any car model. Porsche owners may be a bit more vocal about their problems..but then there are whole series of BMW engines with many more failures.
Yes it does happen, yes it happens under any use condition, no Porsche does nothing about it when the collective opinion of the owner's community is they should.
But is it a wonderful car...you bet. Reliable compared to many other sportscars including older Porsches, yes. Mine more reliable (based on # of trips to the dealership and cost of unscheduled maintenance per month of ownership over a 40-55k miles on each car period) than my Honda or Acura.
If your risk tolerance isn't sufficient to take a chance, you shouldn't be buying any car without a warranty. Buy a CPOed Boxster from the dealer and pay the dealer premium and the CPO cost for the car.
Or buy an Extended Warranty. Statistically far far worse than going to the casino but there for those who can't (or don't want to) take the risk of a major system failure costing big $$$.
My
web site has all I've been able to collect about the good and the bad, about buying and how to limit your risk (say PPI).
Good luck in your decision.