I find pretty decent 80's Japanese bikes set out for trash all the time (panasonic, schwinn-le-tour, nishiki, centurion, to name a few). I also picked up a nice mercian racing frame once. I built it up and rode it for a year till a better target was found. I ended up selling that frame on ebay for $120. There are lots of treasures to be found set out for trash. In my area the best times are late summer and early spring (probably garage cleaning days).
Another possibility I haven't tried yet is checking dumpsters behind LBS's. I've been in stores when a disrepaired but potentially restorable bike came in for fixing. When customer is quoted $200+ to get it running, they just leave it. The LBS walks it out back and tosses it in the dumpster (seen it happen twice).