Geri, If you're not as interested in making money as you are in being free of the treadle, you can call Goodwill or Salvation army and they may send a truck out to pick it up for you. Then they'll give you a receipt for the value and you can claim it on your income tax and take a write off. I have done this in both Ohio and North Carolina. In Ohio I gave them gymn equipment and a sewing machine. In NC, I gave them a huge Turkish oriental rug made of lamb's wool. I tried to get them to take an older electric stove and a console stove, but they said they were too old. The rug was 30 years old, but they were happy to get it. I don't know if they would want your treadle but it's worth a shot.
I have bought a vintage Kenmore sewing machine and cabinet on eBay before. As long as you package them up properly and insure them, you should still consider that an option.