RE: Costs of Protection
Most states allow lethal force for defense, however, most states WILL arrest you for it, and confiscate at minimum, the weapon that was used.
If you use a weapon more powerful than the weapon the person breaking in is threatening you with, most state will convict you. If you do not get a direct frontal shot, stab, most states will convict you.
I have a friend in MI, came home after a graveyard shift, was hit in the head and left for dead. He woke up and heard his wife screaming, he took a knife from the kitchen and found the burgler holding a gun to his wife and raping her... He killed the rapist... He is serving a 25 year sentence for murder, his life was not directly threatened at the time and he stabbed the rapist in the back.
His wife left him after he was convicted.
WA has the most liberal self defense laws that I know of. I have heard OK is even more liberal, but have no personal experience with it.