Currants in NJ
Not a direct source, but here's a local point of reference and may be worth a call:
This is a small farm in Kendall Park that grows and sells red currants and other specialty berries to local restaurants and stores, unfortunately not to the public. They do sell plants to the public if you have the space or interest to grow your own.
Also saw on their website that black currants can only be grown in NJ with approval from the NJ Dept of Ag - may explain the lack of local berries.