hey HTC, notice you're in a confusing spot. although im but a teen, I know a thing or 2 about the value of these trucks.. i have seen some 40's era bolts in questionable condition acquired for rather high amounts. but in your case, especially the way you described it, the owner may be going a couple hundred too high. most of the damage doesnt sound bad, but if you say the bed is rotted, that by itself is a rather expensive fix (about as much as the asking price.) if it were me, i would work him down to around 7, 800 bucks. then you'll have the extra few hundred you didnt spend buying the rig to put towards refurbishing the bed.
keep us informed, it'd be much appreciated