I recently ordered bobbins from nancysnotions.com . You can call for a free catalog at 800 833 0690. I called before I ordered the set to ask about the return policy should the bobbins not work. No worries Satisfaction guaranteed. The bobbins worked like a charm in my Bernina. The Nancy in the link is the Sewing With Nancy you see on TV.
The bobbins are listed under, European Set, then you see the choices of Bernina, Pfaff and Viking. I ordered the Bernina bobbins : 20 bobbin Value Set on sale for $15.76, usually $22.76 last month and free shipping offer.
Of course you will have to check the current price and shipping as it may have changed.