Should we kill healthy people for their organs?

I don't agree with this unless the person does it by their own free will.
If you just go around killing people for the "better good" what is that saying to everyone?
That killing 'healthy' people is ok as long as it saves someone else?
And what if people began to abuse this by killing people and saying "Well, I needed their healthy organs"
Also if I had to shoot someone why would I not just shoot the kidnapper?
I have a gun and even if theres more of them I still kill one of the 'bad guys' right?