Good luck finding anything like caps and powder at a local store. It's not that they can't get them, or that they don't want to. It's a case of it's not economically viable for them to stock a few caps and a couple pounds of the holy black on the off chance of you strolling in and buying them.
Your best be for anything consumable like powder and caps is online. Yeah, there's a hazmat charge but if you pool your order with some reenactors or a NMLRA Charter Club, it goes down fast.
Past that, avoid CCI current production. They're garbage for any kind of accuracy work. The old 6 wings were the gold standard till a reenactor sued them and they quit making the good stuff. These days it's RWS or Schuetzen.
IIRC, Schuetzen is located in TX, do some research and see if you can get some caps from them.