David, I don't know of any commercial sources. I obtained mine from
Paul Otten of Natura Farms in MN. Though he has long since ceased mail
ordering, he does offer a limited number of "dig your own" currants for
the local market. So for out of state queries, I would be willing to
offer some cuttings (preferrably as a trade) late next winter if you
remember to bug me early next year. . .