Sew-classic does carry them. However, they are now recommending a specific plastic bobbin instead of their metal bobbins. The note on the metal bobbins page said they used to test each metal bobbin before they sent it out to be sure it was ok, but can no longer do that and recommend one of their plastic bobbins.
I have purchased the class 15 metal bobbins from them in the past and no problems, and their plastic ones also, no problems. Their metal ones are on clearance, so I suspect they might stop carrying them because of the quality. Just a guess.