Cruise some craigslist, thrift stores, flea markets and such. I got a fujica single 8 for 30 bucks at a local thrift store a couple months ago. If you're impatient, Ebay isn't a bad option either.
Also, get ready to spend lots of money if you want to get it telecine'd. The film and the processing are a lot cheaper than 16mm but digital transfers are just as expensive. A 50 ft cartridge (about 2.5 min of footage) will probably run you 45-50 bucks between buying the film, getting it processed, and getting it telecined.