Interesting read.

http://www.datacenterknowledge.com/the-facebook-data-center-faq/

"The company doesn’t say how much it spends on data centers exactly, but some of the numbers usually make it into public filings. The data center it is building in Fort Worth, Texas, for example, is expected to cost about $500,000 initially, but as Facebook expands on the site, its investment may reach as much as $1 billion. It is expected to invest about $250 million in the initial build-out of its data center in Los Lunas, New Mexico.

Facebook reported $2.52 billion in capital expenditures on data centers, servers, network infrastructure, and office buildings in 2015. That number was $1.83 billion in 2014, and $1.36 billion in 2013.

It owned about $3.63 billion in “network equipment” as of the end of 2015 — up from $3.02 billion in 2014.

In 2015, Facebook spent $480 million more on operational expenses related to its data centers and technical infrastructure than it did in 2014, according to an SEC filing. The company told regulators it expected this expense to grow further in 2016 as it continues expanding its data center capacity."