I wouldn't count on it. That plate stuff the army uses isnt even 100% foolproof, and its a very small plate that doesnt cover your stomach or shoulders.
Edit- OP posted while i was
different states and municipalities may be different, but for the most part anyone except felons can own body armor. If you can own a gun, you can own body armor.
I've never shopped around for type 4 or ceramic plate vests. I have no idea for fair prices or good deals.
Also- its my impression that a ceramic plate will take one hit, get a crack, and be vastly reduced in effectiveness after that. So it will really only protect you for one shot, directly in the lungs, not from very close ranges, and even then only if youre lucky.
I realize im sounding very pessimistic. Please dont take it that way, I want a vest myself.