no service records? (even hand written logs of oil changes) i'd ask for a little more $ off. 11-year old car with original brakes / clutch? have they even been flushed? the spoiler should go up after hitting 70mph and come back down when you hit 50. it should not stay up when the car is turned off - might just be a bad fuse if it's not moving. could be the motor is no longer functioning (would be surprised if that is the case though). would have been surprised if the IMS was done. if it were then i would "feel" better about it since the owner is knowledgeable about what it is and why it should have been done. 11 years old and that mileage works out to around 4700 miles / yr. meh.
if i were the one looking at the car:
1. i'd want to haggle it down to around $10-$11k. because there are no service records. service records to me are more important than "it looks nice."
2. check the coolant tank cap and make sure it's updated. see if it looks like there was any leaking (look under the carpet in the rear trunk.) what color is the coolant?
3. does it have the owner's manual, tools and spare? radio code?
4. i'd certainly want to get a PPI done and walk away if the seller balks at the idea.
mike focke has an excellent write up. go check it out.
http://sites.google.com/site/mikefocke2/buyingorsellinga1997-2004boxster