I paid almost 4 thousand less for mine (also a 99) and at the time it only had 61K miles (I drive a lot) just last summer, and it's in the same basic area...I should drive up and take a look at it, it's only 15 minutes from me.
Granted mine was bought from a private seller, but still, that is a ton of money for a 99, although cars always seem to cost more around the chicago area than anywhere else close to here
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1999 GTP, 105K
Alpine w/ Bose, HUflushmount, volt booster/alt rewire, summit muffs, ss tips, CAI, 180*, ZZP 1.0 PCM, SE Rims, D/S Rotors, some cool gauges