I am not that familiar with prices on all the different treadles...I think condition does play a big part in price, especially the running condition...as I am the proud owner of a Singer 66-16 in the original 6 drawer cabinet that I inherited from my great-grandma, I have to say that I would definitely give one of them a look! That is the good thing about how each one of us is different, and if we all liked or disliked the same things how dull the world would be!!
Good luck to you, and I know there are a lot of vintage machine lovers on here who will chime in soon...
Kif