Don't forget cylinder cracking, or bore scoring on the M96/M97 motor Porsches. Most of the recent "motor failure" threads on rennlist are from cylinder scoring, see almost no IMS issues anymore. Most of those that will go have sorted themselves out already.
Don't get a cheap Porsche if you can't work on it yourself. They're easy to work on, parts aren't bad, but typically the lower-end of the spectrum cars will have a LOT of deferred maintenance to do- brakes/rotors, motor mounts, air/oil separator (which is a bitch), control arms, strut bearings, pinion bearing, coilpacks, ignition cylinder, water pump, radiators, etc which will kill you if you don't DIY