I know that a REAL, Class 3 machine gun STARTS at about $5 grand and gets crazy expensive from there. I've seen some upwards of $50,000, PLUS there's a HUGE jump-around to legally purchase one.
I'm perfectly OK with that and the process to obtain one.
The problem, as has already been pointed out, ad nauseum, is that decent, law-abiding people are not the problem.
I've got one of the rifles on the "ban" list. I've never killed anyone with it. Never even been tempted.
I'm sure that is a common theme with 99.99999999999% (warning. made up statistic intentionally done to make a point) of gun owners across this country.
The solution to the problem has to actually address THE PROBLEM.
People who want to do harm to other people.\
Any solution that doesn't address that is going to be useless.