I think you landed a pretty decent deal. No need for buyers remorse with an Airstream. We looked at a 1971 25 foot International last year with a solid price of $7200.00 to use in smaller areas than towing the 31 footer. I thought that was extremely pricey, it was pretty clean, but the awning had been torn off and needed to be replaced as well as where the brackets were needing to be patch. You could see where it had leaked, and knew this would cost some money to fix nicely.
I then came across a friend who knew a friend that had a small 1958
. They wanted close to $4000.00 and it had to be put on a flat bed trailer to be towed back.
So looking back, if I came across something like you found that needed to be cleaned and some systems replaced for $4500.00 I would be very pleased. So should you.
It may need some work to make it road worthy and comfortable. But if and when you get discouraged, you can find in most classified sections of the paper, a ten year SOB for sale for about $4500.00-$8500.00. New they go close to $18-28K, so folks buying them think they are getting a good deal in which they are by saving lots of money.
You guys got a great deal just due to the history and the Airstream community.
Welcome aboard and make every breakdown an adventure as things will work out, just fine, hopefully.
Best of luck!