I think it's missing the point to even talk about the operational cost of running the iTunes store. It's a strategic play equivalent to the setting up of tollga

I think it's missing the point to even talk about the operational cost of running the iTunes store. It's a strategic play equivalent to the setting up of tollgates on rivers in medieval times. The one most consistent theme across all of Apple's decisions is to not let go of a vice like control of access by third parties to their platform. My personal belief is that they know the future value of owning the tollgate that everyone must pass through to get digital products and information to consumers is far greater than even their hardware business is today. It may not manifest in raw numbers directly (yet) but in terms of the position of power it puts them in its value is incalculable.