I went to a gun range and got very clean lead its just like big lead shot and got about 500 pounds for under 50 bucks. they told me 10 cents a pound. They had about 6000 lbs on hand.
I went to the gun range and got all I could carry for free, but it wasn't very clean. I loaded most of it up into sand bags. Primarialy as an experiment I melted 50 pounds down and made a bar.