I would look on Craigslist for a vintage machine. I have a pink '61 Atlas (Japanese made, all metal- runs fabulous) $28.00 and a 1953 Singer 15-91 ($60 in perfect cabinet).
You cannot buy a machine likes these today. The 15-91 is a total workhorse- will sew through leather, and is a straight stitch. The Atlas will do zig zag and some fancy stitches with cams.
For your money- buy one that will never wear out, that you can oil yourself and has no plastic parts. My new Juki, which also fits that description, runs about $700.00, but for less than $50, in a thrift store or on Craigslist, you should be able to find what you need. You will never regret it.