Although GPS is free for the world to use, it costs $2 million per day to operate. The money comes from American tax revenue.

$750 million

…the annual operating cost of the Pentagon’s Global Positioning System, according to a new Congressional Research Service report. GPS is a constellation of 24 satellites that now can tell everyone where he or she is in the world (the initial constellation cost $12 billion to put into orbit). The operating cost works out to just over $2 million a day. Quite a bargain when you think about it.

Source: http://nation.time.com/2012/05/21/how-much-does-gps-cost/