Of course, it's impossible to know how many sensors the aerial mapping/intelligence folks are buying... Some of that work is commercial, for everything from real estate development to agriculture and forestry to ecological science (even those numbers are hard to get, but there's no reason they should be impossible. A largeproportion, however, is classified spy secrets.
I once talked to an engineer from Cray, and I asked him where and how they tend to sell their machines. He said that a lot of them go to everything from universities to the National Weather Service to biotech companies (and at least one baseball team, which I found out years later). When someone like that buys a Cray supercomputer (for millions of dollars) it comes with some Cray engineers, who move into the customer site for weeks or even months, integrating the machine into the work environment and making sure everything is running well. On the other hand, they get orders from Langley, Virginia and Fort Meade, Maryland where they just drop the computer off on the loading dock and some folks in trenchcoats come out and move it into the building...