Jelitto Seeds carries these seeds. They're pricy, and there is also a minimum order, but if you can't find them anywhere else, you coan get them there.
I'd be happy to share some. These are, however, dated from 2009 and I've noticed a distinct degradation of viability with the Cherry Brandy rudbeckia after just a couple of years. T-mail me if you'd like to try some of these.
Confidence is that feeling you have right before you do something really stupid.