Both trailers are in good usable shape and both are worth what someone is willing to pay. I think $6500 is a bit much for a '99 but that is a heck of a lot of trailer. You might go a long time to find another of that size in that condition.
The tires are 8 years old and if not used on a regular basis, would be beyond usable life. They might make the 440 miles if you take it slow and easy. Since you have six and are probably going to be shopping for a good deal, I'd try the trip home. You do have a spare so that should ease some of the worry.
