it is usually (best/biggest selection) to hit the Auburn/Chord auction in Auburn Indiana for good deals on muscle cars in good condition... (that auction was the first weekend of september)
but, I know of one quality dealer that doesn't deal in crap... thier asking prices are a little high, but I'd tend to think they are much less than most deal's you'd get in Florida, and California...
http://www.centurybuickgmc.com/gilmo...ct/contact.cfm
the Detroit area will almost guarenteed have the best prices on any condition muscle car; just because they are so prevalent. I can pick up the local muscle trader paper, and do some research.
also, to get an idea of cars in and around the places you are going, this is a great resource
http://www.oldcartrader.com/ocsearchform.php
BTW, so i can keep my ears open, which year range, and car model is perking your interest?