It will be worth whatever it is to the prospective owner.
There are many variables that would determine value.
Is the frame and floor rotted?
Have the axles been replaced recently? If not then they're going to need to be.
Is the interior complete and in good shape?
The last one is the big one. If you have a complete interior with all the original bits and pieces it will add trememdous value to the trailer as there are so many gutted ones for sale and people don't know how to restore them properly.
If gutted, then IMHO she is really only worth what someone would offer.
Per Mare, Per Terram and may all your campaigns be successful.
“It’s a recession when your neighbor loses his job; it’s a depression when you lose your own.” "Harry S Truman"