Lots of repairs needed, tires are most likely timed out by age . IF it is structurally sound that is what is important. I just purchased a unit with issues but those can be fixed. It's really a **** shoot. Start with average retail minus add up what it would cost to repair the broken items. Faulty switches, valves or whatever doesn't chase away everyone. A motorhead like myself looks at that as fun stuff. If it doesn't leak, no frame damage etc that's what is important. Graphics? I see tons of trailers out in the desert with no graphics. The appliances in RV's are throwaways. After so many years they get tossed for new ones. The RV'er who can't replace a fuse is not interested in your unit however those like myself are looking.
When selling my vehicles I price them high, I have service records and fix anything that fails. I price them high then wait. Then I start dropping the price and bam the buyers come alive.
I ignore the low ballers who are imbeciles and those interested come forward. It takes time but that's ok. Look for comparable and adjust accordingly. Great time to sell as new ones are slow
coming out.