How close is KBB for REAL Porsche Value?

[driftguy]

I'm considering posting my Box up for sale or even trading it in and like every previous car I've owned I ran to Kelley Blue Book to get an idea of what I can expect as a fair offer. To me, KBB seems under real world prices a significant amount for Boxsters. It valued the Box as a trade-in under $9,000 and even a Private Party sale was hardly over $11,000. I took a look on Cars.com and Autotrader in the 250 mile or so range and found several Boxsters to run comparisons on. Each one was for sale much higher than what they actually "should" be for sale according to KBB. Even compensating for negotiation room, I can't imagine someone would post a car for sale, whether a dealership or private party, 3-10k MORE than what KBB would recommend. What am I missing? Is the market value really that much different than KBB for Porsche? Or are these dealers/owners just wishfully thinking and sitting on these cars for ages?

Anyone care to throw a number out there for what should be a "reasonable" value for trade-in of my Boxster?

1999 2.5L
Manual Transmission
33,000 miles
Bose System w/ Door Speakers
Factory Amp
Power Seats w/ Memory
Cruise Control
17" Turbo Twist wheels
New Upgraded Soft Top with Glass Window (GAHH equivalent)
Tinted Windows just done a week ago (legal limit of course)
In Superb condition, new tires, freshly repainted and repaired passenger side door (too many dings), repainted rear deck lid with new Boxster script, repainted front and rear bumpers and new bumperettes. The interior is immaculate with no wear, scratches, and everything functions perfectly. It almost looks brand new.