Try Auto Trader Classics...everything, from time to time, from Concours to wrecker refuges...
The listing below is showing Scottsdale as "ground zero":
http://www.autotraderclassics.com/fi...l&refined=true
You can also try "Hemmings", "Wheeler Dealer", "Deals on Wheels", "Racing Junk", "Kijiji", and a host of others. If you're looking for a "project", there are guys all over North America with multi-listings that may not be Camaro-specific.