Have you tried Thornton Cabelas? I saw somebody buying some blackpowder today. Also, there's a reloading shop in Brighton (RMP Reloading) that has been getting in some powder that you may want to check.
They run small. I'm not sure where KUIU gets their manikins, but they're small replicas. I typically take a medium or large on some other clothes but always XL with KUIU.
When I went the guide had a spotting scope and range finder. I wouldn't skimp on sleeping bag, tarps, or rain gear. If you get wet, you'll be cold and miserable. I would also toss in some plastic trash bags to keep other things dry. Headlamp should suffice for a flashlight.
I hunted a few years back for Dall Sheep with the outfit that Billy was associated with. He wasn't my guide but I had a chance to meet him and his client was successful and very happy with the hunt. Great guy, in fantastic shape...I wouldn't hesitate to go out with him for any species.