Yes - the cost of "hobby items" are driven more by some perceived ability to pay than any actual production/transportation costs to get the product to you.
Compare the cost of a "marine part" to a regular "automotive part". No reason for it to be 4 times as expensive, but the obvious thinking is, if you can afford the boat, you can afford to pay a premium for owning one.
And the cost of items is set according to the standard of living of the people buying the product.
If the "end user" can't afford 20 or 30 bucks a pound for black powder, then it won't sell at all or it won't sell for that.
The Chinese probably burn more black powder in the form of fireworks than most of the rest of the world combined. I can't see it being worth 20 or 30 bucks a pound over there where a well paying job gives you 250 bucks a month.
So yes, as a "rich" American (Canadian, Western European etc) you can AFFORD 20 or 30 bucks a pound IF you want to pursue that particular hobby because you spend more on lunch at McDonald's than half the world makes in a week in wages...