Yes, $7k sounds decent. Not bad at all, assuming it's in good condition. I hope things soon get back to normal so you can get out with it and camp. In the meantime, there's always 'driveway camping', which not only can be fun but is actually a good idea, sort of a practice run to see how things work and what you need to pack.
We FGRV folks tend to divide trailers into 2 groups: all-molded bodies and those that have non-molded panels. The latter we tend to call "stickys" or "stick built" out of old habit, although many of them now have aluminum framing inside the laminated sidewalls instead of wood studs. The thing is, all stickys have seams between the sidewalls and roof, and eventually those seams might leak. By contrast, all-molded trailers don't have such seams. They can still leak around window, door, and vent openings, or from inside plumbing, but they don't have those seams, the additional potential leak points. I'm just explaining some of the terminology you'll find as you peruse the posts and threads on this forum.
I'd be interested to know if the sidewalls on the Aereon were flat, molded panels (fiberglass through and through) or the more usual lamination (which often was a foam-and-wood sandwich with FG gel coat). On the one hand, a laminated wall will have a greater insulation factor. But on the other hand, if water penetrates, it can swell the wood part of the sandwich and delaminate. Do you happen to know which type it is? I don't. Either way, periodically inspecting the seam and adding the appropriate sealant will be important.