James Hamilton (VP & Distinguished Engineer, Amazon Web Services) posted his data on the cost of a data center. The original page with the explanations can be found here: . He also prepared a spreadsheet. You can find a copy here: File:PerspectivesDataCenterCostAndPower.xls.
The starting point of the analysis is the critical load.
He posted more data in the following presentation: File:JamesHamilton AmazonOpenHouse20110607.pdf.