Not sure how things are up there, but around my area, the cabinet is going to determine the value for a machine in that condition, since the machine would be about $15 on a good day.
If the cabinet is in bad shape, then $25 may be all it would sell for. If very nice shape basic treadle, then $50, and at the top end, if pristine parlor cabinet with embossing, then $400 if you get someone like me that really wants the cabinet and does not care about the condition of the machine.
If the machine has been serviced and works well, then someone may pay $100 for a good usable machine - most of the value is in the servicing.