Asymco analysts compiled their findings and estimated iTunes costs Apple over $1 billion a year to run and maintain. With a cost of running a store this large, Apple must be making a considerable amount of cash, it's estimated to be around 10%, which would be enough to cover operating costs. Apple also takes 30% of the sales from Apps, but that also is to cover the operating costs of the data centers and bandwidth.
Asymco estimates that iTunes costs Apple upwards of $30 million a month to run in 2009, but with an ever increasing market, that price could have jumped to over $75 million a month. That calculates out to just under $1 billion dollars a year, not to mention the TV and Movie store Apple also has.