"The eager are not experienced and the experienced are not eager."
Welcome to the forums!
Given your plans to gut (or start over), I would not pay more than $2500-$3000. The problem is that you'll undoubtedly have structural issues to deal with (rear end separation/floor rot/frame rust) which will slow you down quite a bit.
Here's my general view of units for sale and price ranges:
$9000-$12,000 - original owner condition or competently restored
$4000-$6500 - all original (including appliances) with hidden problems which will either be addressed (costing possibly thousands more)
$2500 and below - obviously fixer uppers, but well worth it for the one willing and able to restore it (look for straight shell above all else, but plan on structural repairs and appliance replacement)
There are obviously exceptions to the rule, but I would try to avoid the $4000-$7000 range as I see that as the "get burned" range
With all new appliances (nearly a given, in my opinion if 20+ years old), you'll eclipse $10K pretty easily unless you're extremely handy and frugal.
I don't think most newbies can imagine the sheer number of hours involved in a restore until they've done it, and once they have...$10,000 looks pretty cheap when they factor in their time.
Given your chemical sensitivities, this could be an even more challenging task than most of us have already undertaken. I would seriously evaluate this before proceeding further. As a father of 8 (15, 11, 10, 9, 7, 6, 4, 1) and yes, we homeschool as well, I have spent more time away from my family than I care to recount, and while I'm happy with my custom Sovereign, I'm not sure it was worth all the hours I missed with my family (not to mention my frustration during the process).
If I were in your shoes, I would not take on a restoration project but look for one (and be willing to pay for it) already restored with which you can make minor modifications. But I've done two Airstreams (
72 Overlander,
73 Sovereign), so my opinion is obviously a bit jaded.
Good luck in your pursuit!