An option, though more expensive than the salvage yard, is Non-Ferrous Metals in So. Seattle. They sell pure lead in 2.5 lb ingots that will easily fit into most melting devices at about seventy cents a pound.

My personal view is that the risks associated with melting and casting lead i.e. inhaled toxic fumes, incidental absorption through the skin and risks of explosion due to moisture (it only takes one drop of water) are not worth the premium price I pay over the course of a year for lost store bought lead weights and jigs.

If you are intent on casting your own lead products, heavy gloves and coveralls, safety glasses, a stable work station and good ventilation (outdoors and undercover) are a must including keeping the kids and pets away from your work area.

Just my two bits.