I agree totally, esp with cars such as these, it having the the engine trouble maybe the straw that broke the camels back. There is most like plenty of other hidden issues not disclosed or forgotten about because the owner just learn to live with the issues. Always assume the worst and check what you can to solidify condition.
Reread this thread about what goes wrong to remind you of the common issues.
http://986forum.com/forums/general-discussions/14685-thinking-buying-boxster-must-read.html
I've had several of these cars and if you are thinking buying to resell... well you better already have a parts car to donate the parts and willing to sacrifice your time.
Remember to check the registration and see if there are back fees.
Get a check list beforehand as it is too easy to get emotionally involved with the car when you are there.
Oh another reminder...
Theses cars are a hard sale. the majority of the cars you see asking near retail price, have been for sale for months!!!