I tried this a few years ago and I can really attest to just how awful an idea buying a used machine is. I found a decent condition one on craigslist for $100. I bought it, and it's been stuck in my garage for 2 years now. I must have gone through $200 of parts just trying to get the bill collector to work, and it still doesn't. It would be at least a few hundred more to bring it to a place that can fix it. If you're thinking about doing this, you need to make sure that every part of the machine works, because if you're just starting out I can guarantee that you won't be able to do the maintenance yourself.