I live on the coast opposite the bay area, but I'm Italian and from the Philadelphia area. Therefore, I know with certainty that the best place to start for any sort of pork product is with a butcher. If you don't know one, google it, and call until you get the answer you want. Butchers are meat professionals, they will find you what you're looking for.
If you're really in a bind, something tells me Dean and Deluca could probably source one for you, but it will cost you a lot.