I got my first one at a very large antique shop for $185. The cabinet is in great shape and the machine head still has all painting on it. It may sound high but I wanted one really badly.
My second one I bought from a local person who listed on CraigsList. I got cabinet and machine for $50. It really needed rescued!! I took the machine head out and it is with a repairman for cleaning and whatever it needs.
So depends what you want--a fixer upper or one in good condition. Have fun looking. Hope you find what you want.
Chris