You can buy individual blocks and/or bags of Grande from
Vinny's Italian Grill and Pizzaria. Corporate policy is that they sell every ingredient they use, be it cheese (Grande), flour (All Trumps), tomatoes (Escalon and stanislaus), spices, pastas, OO, marinated artichokes, balsamic,
etc). I buy individual 7 lb. blocks of whole and part skim mozz for $19.26, including tax ($2.75/lb.). If you ask nicely, they'll sell by the lb. for a few cents more/lb.
I've since found out from the manager of the Hillsborough restaurant that his brother and sister-in-law own a mom-and-pop Italian restaurant in Durham (which happens to be my favorite Italian restaurant), and that they'll sell Grande, All Trumps, and 6-in-1 to customers if you ask.