JSF,
I don't know if you know any telephone company repairmen. If you do, or if you can catch 1, ask him if you could get some sleeves that they use to seal repaired multistrand wire bundles.
I think what they do is slide the sleeve, like a lead pipe, over the busted wires, match and mend the wires, then slide over the repair and crimp down on the insulation.
When they need to remove 1, it's no longer usable. They might be willing to give them to you.
Another is to ask any plumbers you know to save you the old lead pipes they sometimes tear out of old houses, or a demolition company, the same. Don't pay too much for lead pipe, if they sell by the pound, a lot of the weight would be a 100 years crud buildup in the pipe.
Your 12 bucks a bag shot is damned cheap, actually, last store I was in, for a transfer, was asking 19 bucks a bag. Last time I bought it, near 30 years ago, paid 4.50 a bag, bought 500 pounds at a time for trapshooting.
That's as cheap a source as I could imagine you finding, for commercial lead. It DOES have some antimony in it, how much, I don't know, so it will be a little harder than pure lead.
I don't know what wheel weights are made of either. They should be close to pure lead, as if they are of lighter alloy, like 40% tin, they will be bigger than pure lead, and they don't want to make a weight any bigger than needed. And, lead is the cheapest part of the weights. Way cheaper than tin and antimony. Well, mebbe the piece of steel for the clip is cheaper, but you know what I mean, just if I don't add that, I might get jumped on. Not a hell of a lot gets past some of you guys.
I'll have to research that. And I gotta do what I just told you, need lead. Last I got, my s'inlaw's dad gave me, after I asked if I could buy some from him. I know he's down to his last 16-1800 pounds. Way better scrounger than I am. Course he's older, near 70, I'm still in the lower 60's, but I'm learnin'.
Cheers,
George