Given the pricing deal it can't hurt
at all to have a PPI done, so I'd say do that for sure.
Also read here:
Boxster Buyer's Tips
Mike Focke also has a webpage that I cannot pull up at the moment, but I will edit my post later and add his site in unless someone else would like to beat me to it. He's also got plenty of good information.
If she's just selling it that low because it's of no use to her, then you sure will be getting a deal should the PPI have good results.
Don't feel any shame, it being an S you'll still have plenty of fun with a Tiptronic. Do a search on here for "kickdown switch" and see the lil trick these cars have up their sleeves...er, vents, rather.