It's getting more difficult to find free wheelweights.
When I pay, it's about $0.10/lb ($20 for a full, "clean" 5 gallon bucket - about 175 lbs that yields about 125 lbs of ingots). By clean, I mean other than dirt, some paper, and rubber valves, there are no brake calipers, large bolts, etc., and no moisture to speak of. I once got a free bucket that had a couple of inches of water in the bottom and at some point had a bunch of oil poured into it. Not a pleasant experience smelting that, even when it was free.
P.S. the best times to score are Oct-Nov and Apr-May, i.e. "Tire Season". Most large tire shops have contracts to have their wheelweights taken away, but most general purpose shops don't. I find it best to offer to pay up-front starting at $10/5 gallons - sometimes I walk away with it for free. When asked "what for?" - sinkers, toy soldiers, or bullets for competitive target shooting.