I'd advise being open to spending more than $25. My neighbor sold a 6 yo $2000 Lemond for $500 that had close to zero miles. That's a bargain to me.

I picked up a Raleigh for $25 that I foolishly resold (too big) for $45. But I've never stumbled upon anything close to that deal since. I think a lot of what would have been garage sale bikes goes on craigslist these days, at least in my area.