Here is a site for prices for the cases and bobbin case:
http://www.221parts.com/bobbin.htm
http://www.sewingmachinesplus.com/P60221NS.php
My concern would be the sticking--is it gummed up? is there a needle in it that is bent?
All the parts can be replaced if you only want a featherweight to use, if it is one for 'antique' then you need to wait for a complete machine.
Me, if I thought I'd be able to get it running I'd give $50.00 for this one. I gave $100.00 for mine without electric, case, and attachments. I already had the attachments....