What's a 1988 28ft Avion worth?

[mcgailliot]

I'm looking at buying a 1988 28ft Avion trailer the owner is selling as is. The trailer is clean with normal wear and tear, and no updates. Trailer lights won't come on when hooked up to 120volt. Batteries are from 2005 so can't tell if electric jack works or lights for that matter. Trailer has sat for approximately 8 years. No idea if water lines are intact or appliances still work. Owner parked it with everything working.

Any ideas on what the trailer is worth? Owner is asking $6K and is willing to negotiate. Any thoughts/input is welcome. Thanks!