where do you live?
there are some groups in major cities where you can basically rebuild a bike for free. They teach you how and you spend some time wrenching on bikes they give away/sell and then you can take/buy donated parts (some new/some not) for your own work.
Heck, hook up with a club and you can probably get hand me downs of a lot of decent stuff as other riders upgrade. I've given a bunch of cast offs to ride buddies.