Great Suggestions...Casting your own lead balls is fun, and it is cheap, too. Lots of sources for scrap lead. Air gun or .22 shooting ranges have tons of deformed pellets/projectiles to harvest (make sure to fetch them in a shooting break ), and car tyre shops have lots of used wheel weights as well. Means, the ammo will be for free once you have the equipment.
I will do a video today about the new 12 ball mould by Bells Of Hythe, it makes 16 mm lead balls (.63").
http://www.youtube.com/user/Lampi100#p/u/8/JUUWMxDy9cs this guy does well with clay ammo too.Clay ammo is pretty good; the balls weigh about the same as marbles but they're completely biodegradable, so you can shoot them anywhere and not worry about where the ammo goes, collecting it, etc. Actually it's the only ammo I can find to shoot in Thailand (they sell it in big bags for next to nothing). I'm convinced you could hunt with it, too, since I've broken coconuts and dinted pretty stout tin cans with it.