Keep an eye open in flea markets, thrift shops and GoodWill for dive belts. I paid $2.50 for my latest one, with 35lbs of pure lead in it.
Plumbers lead works very well for muzzle loaders. WW works well as a base for pistol velocities. I'm still working on my rifle velocity mix.
I get my wheel weights at the tire shop I frequent. I have my pressure checked every month, on two rigs, so they are very accustomed to seeing me in there. That makes me a "high volume" customer.
Pops