These types of decisions are very personal. Nobody can answer them for you. But you've asked for comments and you'll get them. Perhaps those comments will lead you to a decision.
Here's a perspective I heard on NPR a while back regarding decisions and how/why to make certain decisions...
Almost all decisions have an uncertainty factor associated with them and this uncertainty (fear) is why some decisions are more difficult to make than others.
For instance, the decision to get out of bed and go to work is pretty straightforward for most people. You get dressed, have something to eat, drive to work, get paid. Cycle and repeat.
Going to the grocery store is similar, and to a great extent is a non-decision because we do it so regularly. We make a list, go to the store, they usually have everything we want, we pay and go home.
Going on vacation is more complicated but still relatively straightforward for most people/situations. You determine that you want to go on vacation, you speak to your family about said vacation, you decide on a budget which is relatively easy to determine (rental car, gasoline, hotel, air fare, sightseeing), you designate a time (weekend, holiday, etc.) and you make arrangements that for the most part are well defined and knowable.
Okay, now to the tricky decisions. Buying an Airstream trailer, particularly your first Airstream trailer. Do I want vintage or new(er)? That part is not too difficult but it's related to several of the following items. Do I want to do restoration or do I want to go camping soon? Sometimes this is difficult because it's the first RV so the whole idea of camping/traveling with an RV is also new, uncharted territory. How much do I want to spend? Seems straightforward but there is quite a bit of variation on trailer prices and Airstreams are not on every street corner so to speak. How long will a restoration take and how much labor must I be willing to provide? Whoa, now the story gets very complicated!
Consider just one of those (sub) decisions for now. Do you want to go camping/travel and how soon?
Most restorations take much longer and way more money than initially predicted. If your goal is to use the trailer and enjoy traveling then forget the restoration approach. Find a good, used late 80's - mid 90's trailer that is road worthy and go buy it for $20k and move on with life.
If on the other hand you want a restoration project, something that costs $3k - $5k initially, then put $40k and 5 years elapsed time then go for the diamond in the rough. You may be the just the person that performs a restoration under budget, in half the time.
There's no doubt a restoration project can result in the perfect trailer for you and your family. But a good, road worthy trailer can be enjoyed now and tailored to suit your needs as you go.
On Edit: I read your other posts and see that you are hoping to find a vintage unit. Vintage is a wide range of age beginning just 25 years ago. There are plenty of vintage trailers that are road worthy and need a little TLC. The trailer you are considering looks rough to me. Our 1992 Classic is very road worthy and is estimated to be valued at $25k. It's not for sale but you can find similar units for that price and maybe less. I know that's the not the $5k - $7k you referred to but you're going to spend way more than $25k if you restore a trailer.
Lucius and Danielle
1992 29' Excella Classic / 2010 Interstate
2005 Chevrolet Suburban K2500 8.1L
2018 GMC Sierra K1500 SLT, 6.2L, Max Trailering
Got a cooped-up feeling, gotta get out of town, got those Airstream campin' blues...