Check your local Craigslist, charity/thrift/goodwill stores + pawn shops, that kind of thing.
I got mine for $20 on eBay, local pickup - although it needed some repair work that bought the price up.
If you can, make sure to try the machine before buying it. Have a scrap of fabric and thread - make sure it actually *sews*. This isn't a 100% percent guarantee that it will *keep working*, but is much better than just running or turning it without thread and fabric (or not testing it at all).
You'll have to buy locally - shipping one would most likely cost more than $30 by itself.
Disclaimer : This post written by a Grumpy Old Man
Actually in the pipes:
- Remaking Ser Loras doublet.
- Luke Skywalker, A New Hope
- Wind Waker starter costume in swim material
Eventually: Paul from Dune, Faramir, Harry Sullivan