I will say for me, having watched my local CL that it seems that terms like "vintage", "classic", or "antique" seem to drive prices up. I have seen several low end, stove-pipe Schwinns listed for $150-$300 and they are gone shortly after listing. These are usually left un-tuned and in original shape, sometimes some cheapy tires thrown on, but around Chicago the hipster scene is growing. It seems a lot of these bikes end up in neighborhoods where the hipster scene is flourishing and most people will buy a bike because of the the name/look than of the original quality. Don't get me wrong, the old heavy framed Schwinns are awesome on Chicago's streets, I had a 82 Conti and loved it, but I also paid $115 for it any it was in great condition, way better than I am seeing now.

I do notice that since some people won't travel there are a few bikes in the far west burbs that are sitting on CL and not selling. So there are some cheaper bikes out there, and usually nicer, but those will sit for a while before being sold.