Actually, when I singled out black smithing, I was thinking about the investment in raw materials; coal, and iron; the basic tools a smith would have to purchase before he could go to work, like an anvil, not to mention shop space, and a forge.
That they made their own gear is a nice romantic fiction. But the trade inventories just don't bear that out. Trade knives were dirt cheap and shipped by the hogshead to the New World. So were all kinds and sizes of axes. Even moccasins were for sale at Bent's Fort.
Bullet pouches, and powder horns, along with their future contents were also items of trade, and could be found at Detroit, Ft. Union, St. Louis, Montreal, most anywhere merchants catered to those in the fur trapping and hide hunting business.
I will say this in favor of making one's own gear in the modern world: It may save a few bucks, and it will definitely give one a sense of well earned pride. However it will take time, repetition, and some failures along the way to do one craft well.
And to anyone looking into a related craft of our hobby, I would advise choosing only one early on, and concentrate on that. Speaking from experience, it's all too easy to get side tracked, spread one's self too thinly, lose focus, and end up doing a half baked job, ending in frustration. Because there simply aren't enough hours in a day.