Hi Jen,
Good luck on your find!
Definitely, +1 on a PPI. Also, don't get stuck on only looking at one car.... there are so many out there for sale. So, take your time.
You can certainly negotiate a deal further after a PPI, if that's the car that you really want. Since there's a lot of good folks on this board that will help you, IMHO, you should post the PPI info to get some feedback.
BTW, here's a good thread that has useful links in it, if you haven't read them already:
http://986forum.com/forums/showthread.php?t=14685
Keep us posted!