I have a 1997 Tip Boxster with 138k miles. My car was one of the first handful to be build in 96. I still have the original engine and tranny in the car.
My only problems are/were..
-Replace convertible top window @ 115k mi - $170
-Front control Arms at 125k mi - $1500
-Transcoolant Valve and Water Pump @ 130k mi - $1800
-Replace brake pads @ 137k mi - $50 (Own Labor)
-Replace struts @ 137k mi- $400 (Own labor)
Other than that my only maintenance is the regular oil changes, tires, fluids, filters, etc.
I guess Ive been pretty lucky so far :)