original Singer hand cranks (not the machine, just the crank) can sell for $75 or more.
It looks like it's got the very old style box for the attachments, and even though it may be missing the front slide, they are not difficult to obtain.
If it's under $50, I'd snap it up in a heartbeat. If it's also got the lid, then I'd go higher. Not that I'd need another machine like that, but I'll grab a handcrank when I can.