Get with a club that makes group purchases, even if you are not a member, perhaps you may find a friend that does. We've got a feller that buys from Metallico by the pallet for casting and they split it amongst several fellers. I've only bought about 500lb of pure lead that way- a bit more expensive than scrap, but very reasonable for pure lead.
Hard shot is too expensive to melt down, unless you just aren't a shotgun shooter. A little bit of tin mixed with pure lead can help fill out in your moulds, but not too much, because it's very expensive and not something to waste, and you'll never get them down the barrel of your muzzleloader if it gets too hard!
