I decided I wanted to make my own butter to go with my homemade bread. It's not hard, but I discovered that it won't save you any money.
Here's what you need: heavy cream, salt, food processor, and a cheese cloth (I tried a dish towel and it was terrible, get a cheese cloth)
Pour in cream.
Add a little salt. I think I did half a teaspoon.
Place butter in cloth and squeeze out the butter milk.
You are left with fairly equal amounts of butter and butter milk.
2 cups of heavy cream produced just under a cup of butter.