Wheel weights are good but not the only source of lead. Much of their mystique comes from them at one time being free and pretty darn good casting alloy with a little tin added. Range scrap needs a little "boost" to be the equal of COWW's but only if the application (caliber/velocity) requires it.
You have to hunt, consistently, and over the long haul to get a good supply by scrounging. You may pay less for it but one should factor in ones labor, time, vehicle fuel, and cost of smelting.
The S&S forum here one can often get ready to use ingots for just a bit over $1.00 a pound, considering many sources of scrap want that much for lead you have to process into ingots to use... it does make S&S purchases very competitive.
If you find a source, take care of it, nurture it. Corporate tire stores will have corporate rules that prevent selling out the back door. Corporate scrap yards generally don't want folks wandering around the scrap yard searching for stuff to buy for liability reasons. Lead being involved just makes it even more of a liability to the corporate attorneys.
Right now a 100# bucket at 30 cents a pound that yields 50# of lead WW's after sorting out zinc and steel costs more than that amount of lead can be purchased for in S&S. Sweater alloys are often no more expensive as scrap than any other lead, or at most a bit more. So if you can find a scrap yard and visit it regular...
Don't forget your own trade bait. Maybe you can't find WW's but can do well scoring solder, pewter, or some printing alloy. Or can score plain soft lead then purchase sweeter alloys to harden it to suitable for other uses. You can cut plain with some linotype and have hardball with BHN of 16 or a good pistol alloy at around BHN 10 for a reasonable cost.
COWW's are just a handy form that was once common, not magic beans. Lots of other ways to scratch that itch.
Buy more than you use and you will accumulate a stash. A little can go a long way. A lot can go a bunch further.