I can say that I've never bought a lead round ball for black powder, ever! My secret, SCROUNGE, hit up everyone you see for lead, it was used in splicing telephone lines for years, just been replaced in the last cpl years, and utility workers threw away TONS of it. Plumbers and roofers also have access to scrap lead. I recently stopped by an old house being torn down and asked about the scrap lead, who knew they used to line bathroom floors with sheet lead? I didn't, but walked away with over 100 lbs free!
The last mould I got was at a flea market, I gave $10 for a RCBS minie ball mould, and a Lee REAL. So don't be afraid to scrounge
I started with a Coleman stove, the smallest cast iron skillet sold, a hand made left hand ladle, and a mould. A piece of broom handle was my mallet to cut the sprue.
Good luck,
Eterry