Hi Nina. Welcome to the forum.
See Price vs. Condition - Airstream Values
I'm not sure if that link has been updated as as steadily as it used to. It should still give some idea. Did the original Suburban furnace
ever get replaced? Is it a more valuable RV electric-propane fridge or has that been replaced with... what? Does the AC work? Still the original Univolt? Window gaskets hard or have they been replaced? How about leaks/floor/rear bumper - body junction? And finally, have the axles been replaced yet?
Unless you can say all those have been kept up to date, I'd say this is in 'as found' condition. Somebody has to (or has kept up) with refurbishment. That should tell you if this really is in "as found" condition. In which case $2500 might be what you could expect to receive from savvy buyers.