Something I personally hold as dear to my heart as the 2nd. I will say good luck, sounds like a nice way to make a little scratch. There's a big difference of a drone flying over my head by you, a citizen, vs ANY agency, this of course meaning me a private citizen. There is definitely reason a police department can use drones legally though, and as long as they don't need a $8000 one with nobody knowing how to fly it, it's likely a good investment, especially if they use a cost effective Phantom over even an inspire, given the noise and flight times considered, they aren't making art, possibly security or rescue, or even if it is a case with a warrant, I hope you steer them in this direction.
Have fun and good luck, sounds like a good deal.