I don't know what the going rate is--I'm sure a lot depends on condition. There is a guy at an antiques mall in Saginaw, MI who has one for somewhere between $800-$900. His machine is complete but it is a bit rusty and the hinge side of the top of the machine is pretty rough.
I'm sure Curtis will chime in with a better idea.
Gotta get me one of those someday.
Tim