No problems getting bobbins and shuttles for this machine. Davis made millions of Minnesota A,B,C,& S and full sized Underfeeds which use the same B&S. I see them on ebay and I'm sure collectors / parts suppliers have some with parts machines or loose. Some use Singer bobbins in there Davis shuttle.
A full set of attachments will be harder to come by and fairly expensive maybe $50-$100 they go for on ebay.
Jon