A lot depends on the condition. I bought my beautiful 1908 Singer model 66-1 treadle in great shape in a fabulous parlor cabinet for $125.
Some people leave them out in the yard in the weather for a couple of decades and then someone "discovers" them and lists them for hundreds, all rusty and beat. You see those all over Craigslist.
If you could show us some pictures we might be able to help gauge the value for you.