We had a Singer 237 that was a wonderful sewer (picked up for $25, but it was well used), and it is treadle-able. Ended up selling it to a niece and she's used it for all sort of projects - she loves buying clothing at thrift stores and remaking it into clothing she can wear - she's 17 and has found a real love for sewing.
We advised another Niece (different family, but they live two houses apart) and she picked up a really nice one in a cabinet for $100 (looked near unused), and then got it all fixed up herself and she loves the machine too - her's went with her to college.
HOWEVER - I think some may be Italian made machines
BTW, the older Italian made Necchis are wonderful machines. I don't think you'd go wrong with one of them, and some do come treadleable too - an added plus.
The holes for the treadle belt
My husband has gone through this one and was impressed at the quality.
If you get one, make sure to get the "goodies" that go with it - they can be rather expensive to buy separately.
