The problem is going to be made worse by finding somewhere that both has it at a reasonable cost and will allow you to mail order it.
I know of at least one place that as of last week had it (and a tasty selection of other powders) in stock. But it is a smaller shop, a long ways from you, and they will NOT mail order.
Sorry to say that things have gotten better in the powder department, but "better" is certainly not great.
Grouse