From admittedly "not the wisest person in the world":

One way to probably lower gun use would be to make the price of the bullet higher. I think one bullet should cost almost as much as a gun and I think bullets should be sold individually.

I feel that if people had to pay a lot more for bullets, they wouldn't buy them as freely.

I'm not the wisest person in the world, but I know if people had to pay $100 just for one bullet, people would think twice about how important it really is to kill themselves or other people with that bullet.

The black market starts appearing when the tax on something goes above 15%. $100 for a single round is on the order of 20,000%. Her suggestion would work about as well as the prohibition against recreational drugs and probably would use much of the same supply chain.

Jeff has other comments.