Hi Chet, and welcome! The latest year model it could be would be an '86. They were only produced from '84-86. The 16' is fairly rare as there were far fewer of them built; rumored to be around 200 of them. It could be worth from $500 to $5,000+ depending on the condition of the trailer, the interior, the appliances, whether or not the axle is in good condition, and whether or not it has air conditioning. There have been a couple of them for sale recently in the $4k plus or minus range. There was a nice one on eBay that didn't meet reserve at nearly $5k.
We bought our '86 16' UHaul
Vacationer for $3750 about a month ago in Arkansas. Since then, I've seen some posts that say this "Buy It Now" price on eBay was too low for the rarity of the trailer. I guess it what seems fair at the time and how badly you might want to buy or sell. Our trailer had a small fridge
(we've put in a bigger one), no propane
tank or cook stove (since replaced and working), but did have a working water system with hot water heater. We've also just ordered a Coleman Polar Cub AC with heat strip. We are tickled pink with the trailer!
We could take it out right now, but probably won't until our first scheduled trip on Memorial Day weekend to Camp Nauvoo (IL) for the Scamp
You didn't say what the dealer is asking. Is it between $4000 and $5000?