Scrap dealers can be a good source. I bought some scrap sheet lead from the local dealer last summer for 35cents/lb. but that was the cheapest I've seen it in several years. Found a shower pan awhile back when I stopped by an old house being torn down. Found about 50lbs of plumbers lead in 6lb ingots in a barn which the owner had no use for and gave me. Roof flashing, goose neck water meter connectors, sailboat keel ballast........ Keep your eyes peeled and every once in awhile you'll stumble onto a deal. 50lbs sounds like a lot of balls, but if you get to doing much shooting, it'll surprise you how fast you can shoot it up. I've probably got 1200 to 1500lbs of soft lead right now, but I'm looking all the time.