Gary
My observation is that pricing of this stuff defies logic. It falls essentially into two categories if you consider both the cost of the powder and the shipping.
When purchased in five-pound tubs, it is 20.00/pound
When purchased in almost the only viable alternative (one-pound container) it is 40.00/pound.
I understand economy of scale as well as anyone but that does not explain the difference in price.
Everyone appears to be charging what the market will bear. That is not the fault of the vendor but of the market. Unless there is some collusion between material manufacturers and material vendors.