Greetings and welcome to the Forums!
If you are in the Northwest part of Illinois, I know of a very nice unit available from a reputable dealer in Iowa. When I dropped my Argosy Minuet 6.0 Metre off at Ace Fogdall RV in Cedar Falls, Iowa, they had a very nice 1971 23-foot Airstream in stock. They are about a three-hour drive Northwest of the Quad Cities. You can see photos of this trailer at:
Ace Fogdall RV, Cedar Falls, Iowa
I have been a customer of the above mentioned firm since 1995, and have been well pleased with every repair that they have performed - - they are a long-time Airstream dealer.
If you happen to be in far Southern Illinois, watch the
Southern Illlinois Trader (one of the inexpensive classified magazines typically found at grocers). The past few years, they have averaged at least one Airstream advertised each month.
Good luck with your search!
Kevin