Hello and welcome to the forums!
What kind of Airstream are you looking for? New, vintage? Somewhere inbetween?
There is a excellent thread on considerations for buying an Airstream I suggest you review. It is generally on newer 'streams, but has lots of things one should probably think about. Here is the link:
Ask any and all questions! This is the place. You might also want to check out an Airstream rally (yes, you would be welcome) to see Airstreams (always tours...) and meet the good folks who own them. You will get lots of great info too!
Good luck! Hope you find your Airstream soon and we see you out camping!
Mrs. NorCal Bambi (traveling in S Tardis)