"I wish I had a swing like that in my back yard"
We got a Kenmore that had been used maybe twice for $50 off Craigslist. Still had box and all paperwork. Looked like it just came from the store. I convinced the wife she would enjoy sewing knowing good and well I would use it more. You don't need anything fancy, just a half way decent machine that you clean and oil like you are suppose to. I think practice and patience are more important. Oh, and when working with nylon especially, MORE PINS!!!!!
I bought and older machine from GoodWill for $29.00 USD. It is a Brother, nice shape, works great.
Then I was poking around the Salvation Army shop, I found a Kayak PFD for $3.00 and a Singer Slant Needle, 1977, everything included, manual, accessories and a walking foot all for $9.00 USD. So now I have two elderly sewing machines, then I went to a yard sale on Sunday afternoon, I stopped to look at a machine, the guy told me it was not working very well. He also said if I bought his parachute he would give me the sewing machine, a US Army duffle bag and a pet carrier, we made a deal for 20 dollars.
All three machines are metal, really heavy, sew better than my newer fancy machine. On the Sally Ann machine I just wanted the Walking Foot, the machine and accessories were cheaper than the walking foot alone.
Keep looking read the Rev's suggestions, they will guide you. Sometimes you can make an offer of a price much lower than the asking price and get the lower price. I make a effort to be respectful when I negotiate for a lower price.