>that puts their bare cost at close to $10.13 per user per month, not including salaries and other operating costs.//
You're saying it costs then 1⅛ cents per search excluding wages and other operating costs.
That seems like they must be vastly over-paying for something? What does that money pay for and who is paying the wages+operational costs?
Edit: this comment [0] indicates every search is actually 3 searches, two at commercial resale rates (Google, Bing) and one against their own index; that probably explains it.