On the theory you get what you pay for, counting all the costs of these uniformed and stealth operatives, paying enough to get quality people and not just anyone who can fog a mirror, we're looking at a minimum of $40k per year per person. For the 300k some have been suggesting that's an annual cost of $12B. That's twelve billion with a B. Now for the 600k just suggested that would be $24B a year. That's compared to a cost of authorizing properly trained and tested citizens who choose to participate in a sensible program of, oh that's right, ZERO dollars.
One security person is better than zero and two are better than one. Then again, when the one is suddenly ill and either can't show up or has to go home the school is unprotected. Then again, when the one lone guard is at the far end of the building and just gets unbuckled and seated and an event starts at the far end of the building the school is unprotected. Then again, how do we pay for it? School districts are broke. They can't afford $24 much less $24Billion dollars. I don't understand why people have such a hard time understanding the most sensible solution. When you have 100 admin, teachers and staff and any or ALL of those 100 can if they so choose be armed and prepared to defend the students you don't have to worry who went to the bathroom or who called in sick. There are plenty remaining just in case.