How much would it cost to make police drones a thing?

Hi guys, I'm in the military in the military police which in my country is for the most part like traffic police for the military with a couple of more jobs. I wonder how much it would cost us to buy drones to do the work of police choppers that we clearly can't finance? How much training would such drones require? How effective would that be? via /r/drones http://bit.ly/2sTShZe