If you can get the machine for $300 - $500 with table and motor it would be a good deal. What parts are missing?
BTW, my Consew 255RB-3 uses "U" bobbins so if you need a machine with a large bobbin, I'd recommend that. They sell for around $2000 now with table and motor, so a used one would be a lot more than $500.
No one lives forever, the trick is creating something that will.