I would have to "guess" if I needed to know the worth of a machine -- my son has bought two for me that have been real bargains -- one a White FW, no case or attachments, but $50, in pristine condition is I think, a good buy. I works great! Then, he bought a Singer 403A for $41 - again, no attachments, but I've got some slant-needle machines with a full box of attachments, and I've been fortunate in finding the ones I didn't have. In general, I don't collect machines, but I love viewing the old/vintage/antique machines, and sometimes I inherit one or two. I did find one for my cousin several months ago, but she paid for it! Now, I need to finish cleaning it up and renewing the shellac!
Jeanette