Discount house sporting goods clerks and managers don't know the difference between Black Powder, and mice feces! Contact the Goex distributer for your state of interest, and he will tell you where the nearest retailer is that stocks black powder. I can not emphasize enough that you are mostly wasting your time driving around from store to store trying to find Black Powder. And phone calls to retailers won't produce much better results. Find other Black Powder shooters at the range, or gun club, and ask them where they get their powder. If anyone is going to know a local source, it will be more experienced BP shooters in your area.
Don't belong to a BP club, or the NMLRA, or NRA? Shame on you. The reason we don't have powder readily available is that there was no one big enough to speak loud enough for us to keep this from happening. If you join these organization, our voices will be heard. The politicians know that that NRA, for instance, can sway more an 12 million votes in a national election, with 4.5 million members, and their families. The NRA guys screwed up, and didn't protest the change in regulations, fearing a backlash against them for being soft on " terrorists". Someone has to wake them up! Lots of our voices, as members will be heard. But one or two voices are ignorred just as they are by the politicians themselves. You might also consider joining GOA, and the Second Amendment Foundation, both of whom have been putting the heat on the boys at the NRA to go to bat for causes the NRA folks think they can't win.