I don't think the answer is an easy one, but one fact remains, all our government personnel from the president on down are protected by armed people, because they found out the ONLY way to stop a bad guy with a gun is a good guy with a gun, if you don't want to call 911 to have them hurry up and send a bunch of guns. So the fact remains...it must be a good idea to have good people armed with guns, and our children are just as important as anyone else. In most cases, a lot more important than government employees.
Far as money goes, the states should flip the bill...but I have no idea why a democrat would bring up the cost at a fed level, they pour money down the black hole as a way of life....for them to complain about spending is really weird.
There is no great answer...but someone being armed besides the bad guy is the best so far. It's the only one that could work at this time.