I acknowledge that the costs are ballpark and not exact, but I was responding to a post that called the costs "negligible" - I was simply trying to quantify a slice of the cost and demonstrate that it can be a significant fraction of your bill. Of course your bill ALSO pays for the last mile infrastructure and connectivity to the hundreds of thousands of other routes carried on the internet. But it's clarifying to see that the data interchange component, which people are calling "negligible" actually is a significant portion of the cost.

My numbers have been called ridiculous by a couple of people now but they are based in personal experience, albeit a few years old, and nobody has posted any other cost breakdowns that demonstrate an understanding of the industry and the costs involved, just "those numbers seem really high!"

The difference between bandwidth and power is that data is NOT a commodity like power is, power is fungible and can be drawn and combined from a number of sources to fulfill the demand, but the dilemma with ISP bandwidth is that in order to satisfy customers the ISP must ensure adequate bandwidth to each individual content provider, and this is a much harder problem.