I haven't sen an issues wit getting any of the grades of BP lately, but i don't buy it from te stores, i get it at rendezvous or from people like Becky and doug at Hillfolk Musket supplies , or from Will Bilozir.
I messed with makig my own quite a few years ago, and with a bunch of other stuff as well, like rifleing my own barrels the "backwoods way" as per the Firefox books. lottsa fun!
Cat