I assume you are talking about a Motorhome?? Based on which area you posted this question.
If you look at other brands form the 80's, you will find they look quite dated, while the Airstream retains an aesthetic quality unlike any other. This contributes strongly to it's long term investment value, and the strength of the market on them. This seems to be moreso for the 31' and under, as they are the hardest to find.
The quality of the product is excellent..the workmanship and materials for the most part make a 20 plus year old vehicle still quite functional, and very usable. The chassis and mechanics are basically GM / Chevrolet, and thus the parts are readily available and affordable.
Like any older vehicle they do and will require maintenance, repairs, and upgrades on occassion as you can tell from reading thru our posts.
In the long run in my opinion, you will be served well by your purchase of an Airstream if it is done with some time taken to check out the one you are looking at, and make sure it is basically sound from the start. Check other threads here for a list of things to be aware of when purchasing, inspecting one. Good luck- and ask any other questions as you go!!