I'm in MI as well, and it does seem that bikes in general have increased. Craigslist, in my experience, is only good if you put an ad out say you are looking for something, and you dont make it too specific. I have found a few bikes by posting ads looking for "that thing taking up space in your garage" type ads.
Last one I found on e-bay over the winter ($320) working on it now.
Also word of mouth and letting your friends know that your looking also lead to garage gold.
I have also stopped at Garage sales, this give you an opportunity to "snoop" in thier garage. I have found a bike or two that way just by asking if "is the bike for sale?".
Generally they will ponder for a minute and say "maybe". then the negotiating begins
.
Good luck in your search!