Thats true, some Cotsco's do carry ProZinc in their pharmacy but not all of them.
The problem right now is there is a shortage of an ingredient used in the manufacture of ProZinc so you may not be able to get it unless they had some reserve in stock.
Supposedly, ProZinc will be available again in the fall? but many of us that will run out before then will have to try a different option, like compounded PZI form a compounding pharmacy until ProZinc is available again.