I first saw that one at the beginning of February when I was listing one of mine on Craigslist. I think the price was $7,500 then and I was listing my 99 with just under 140,000 at $5,500. Mine had a lot of responses and sold easily.
Here's the current CL ad:
The closest ones I have seen that were listed for any less than that have been in the OKC area.
Retroman1969 picked one up and posted the other:
http://986forum.com/forums/general-discussions/54957-bought-beater-boxster.html
http://986forum.com/forums/general-discussions/60509-anybody-looking-running-driving-project.html
It may be a good car, but at that mileage, for a Boxster, it may also be troubled. If you don't know much about these cars, you should really have a mechanic who is familiar with Boxsters take a good look at it (PPI - pre-purchase inspection).
If it has been well maintained and the IMS bearing has been replaced, you could do well with it. If it has not seen preemptive maintenance and replacement of wear items, you could easily spend well over $5k in the first year.
Things that come to mind:
Oil leak - Spark plug tubes, RMS/IMS bearing, AOS.
Suspension parts - Anything with a bushing or boot is probably past it's life expectancy if it has not been replaced.
Cooling - Waterpump & coolant tank.
Wheel bearings, brake rotors.
Correct operation of HVAC, windows, and top.
When you first turn the key, do ALL of the proper console lights come on and go out? I have seen quite a few bargain cars that the check engine light or air-bag light has mysteriously "burned out" in.
If it checks out as acceptable condition, $4,500-5,000 sounds good. Expect to continue to spend $1000 - $2000 a year to keep it good, or a bit less if you DIY.