I suspect the value isn't much different from your '07 price. It's all-about the condition. If it's clean, runs well, doesn't jump-out of 2nd gear on hard acceleration, and needs no battery, no tires, no brake pads, nothing but gasoline, yes, it's worth $3500. On the other hand if it needs all those things, has crash damage, and yes, it jumps out of 2nd gear, I wouldn't give you $1,000 for it.
The '85-'89 had the analog 2 head ignition pickup, '85-'92 had the small front brake rotors, smaller dia downtubes, sliders and triple tree, and 2-piston calipers. After that, there wasn't much in the bike that was different, so a '97 has almost the same equipment as an '07. Yes there were a few minor changes, but essentially the same bike.