I'm a real cheapskate.
only bicycle I bought was $10 at the thrift store.
All the rest were gratis.
Give-aways on CL, I solicit for free bikes on CL, and, I gather up discarded bikes wherever I can find 'em. I also buy 'em for scrap metal value at the salvage yard... which means I get 'em for almost nothing, because they are pretty much a liability for them, being mixed metal, with rubber and plastic and such.
Every so often I donate a bike that is nicer, and clean, to a local charity, and I also give bikes away to local kids in need of basic transportation.
I am a devoted re-cycler, which is popular here in Kalifornia, except with landlords.
Good luck
rc