$25 and up seems about right. I've gotten quite a few free treadles and $5 and $10 ones also. To me $100 is a darn nice treadle but some would spend a few hundred without batting an eye. I'm in Singer country in NJ. A lot of it is luck and regional demand or lack of demand. If your willing to hold it and play around with it for a while than why not ask a hundred or two. Quick sale a lot less.
Jon