Don't forget about Craigslist. I do a search on 'sewing' and 'quilt' all the time. Usually tons of older sewing machines for under $100. I got one for $50 that came in a cabinet. It worked fine until I started dinking with the bobbin case and screwed it up. :( There's a tip: don't dink with what works!
I have the cheap Brother from WM. It does fine for me. I just do basic stuff with it.