I was able to get the bobbin case on Sew Classic (
http://shop.sew-classic.com/) and the bobbin hook assembly and carrying case on eBay (
http://www.ebay.com/sch/Sewing-Machine-Parts). I also found Singer Featherweight bobbins on Amazon.
Grand total for today's purchases:
$190.83
Which covered a bobbin case, bobbin hook assembly, carrying case, and 50 bobbins.