I know a guy who bought his Airstream in 1972.  He still owns it and it works fine today. 
We bought our 73 10 years ago for $6,000.  It is worth more than that today.
The other bonus that most non Airstream owners don't understand is the ease at which they tow.  All wheel independent suspension, low centre of gravity, and aerodynamics allow it to be towed with just about anything with a substantial fuel savings.
PS...  back in the 60's my dad had an RV sales business and sold Mallards....... but he always wanted an Airstream.
Gary T once wrote...."My wife begged me to buy an Airstream. I hated the storage on them and hated the price. That was 3 years ago, Oh my god, I have fallen in? love. I changed my mind when I had to do a sudden evasive turn and then zig zag down a steep hill. The freaking Airstream hunkered down like a Porche and we escaped with our lives. I love my Airstream."