There are really two questions. One is what is a reasonable profit margin for a software distributor. Before there was a app store there was boxed software in

There are really two questions. One is what is a reasonable profit margin for a software distributor. Before there was a app store there was boxed software in brick and mortar stores so there is a reference there. The other issue is that Apple imposes a monopoly on software distribution in their devices. Because of the monopoly no one can really be sure what a fair cut is in the app age because there is no competition.