JoAnn,
I agree with Joe. It would irritate me to the point I'd want to spit, if I had to change out bobbin cases every time I changed machines! JMHO! I have seen some pretty good deals on ebay -- you just have to shop around the site and it is frustrating, I'll grant you that! Good luck! If I happen to see anything while I'm cruising through the site, I'll send you a pm, okay?
Jeanette