One option is to check and see if there is a re-use center near you (a.k.a. "the dump"). I know that the one out here makes you put bikes that you are dumping off in a rack. You just have to show up, tell them your zip code and can take whatever you want. I grabbed an '83 Peugeot that is in mint condition last year as well as some vintage Schwinns. It is always hit-or-miss as there are people that go damn near every day and take stuff to sell elsewhere, but every once and a while you will find a gem that someone thinks is just a crusty old 10-speed, but is in fact a nice lugged steel frame with very nice components.