I've purchased 9 bikes on Craigslist in the past 5 months. My best score was a pair of mint 1984 Raleigh Portage bikes I got for $175. I'm keeping one to ride and sold the other for $290 after a couple of hours of cleaning and polishing and a little grease here and there. So essentially I got a free Portage in my size plus the money to upgrade to barcons and a few other goodies. No secrets, just the ability to act quickly when I find something I want.