What engine/transmission/axles? What gear ratio?
If you have "a little" rust, but a crappy drivetrain, and a base model (no optional stuff to sell if you part it out) then $800 would be on the high end. For example, a 304 (or even worse, non original/ AMC V8), T4/T5, Dana 300 with 2.73's and some rust, with NO TITLE, even with a hard top, probably isn't worth the asking price. On the other hand, if you have a good running V8 with T176 and 3.31's or higher in the front and rear, you've got some good marketable parts.
I figure up what something is worth if I part it out. With no title that's pretty much all you're buying; parts, so it makes sense to take the LOW figure of what the parts would bring and offer quite a bit LESS than that since you gotta tear it down to sell the parts.
If you think you can get a title for it, and can get it cheap enough, by all means do so, but for valuation it's still worth no more (to me) than the sum of its parts minus your time to strip it.
85 CJ7 258, borla header, Team Rush, MC2100 ,optima batt, Warn 8274, agr super box 2 & pump, T5 w/ B&M shifter, centerforce 2, superior 1 piece axles, warn hubs 2.5 in lift, 31" BFG MT
85 CJ7 258, A/C, T176, MC2100, Team Rush, Warn XD8000i, superwinch hubs, 3in lift 31" BFG AT/KO