I think corn cob media must be available in bulk for pet supply purposes too. The guy who runs my favorite reloading shop buys it in bulk and sells it cheap. A bag that's big enough for my cleaner costs $3. It's not treated, but it works as well as the expensive reloading brand of corn cob media. I thought it would be tactless to ask him where he gets it, so I didn't ask. In any case I'm happy that he sells it and I'll keep buying it from him. I can clean about 10,000 45ACP cases with it before I need to pitch it, but replacing it after 5,000 is something I should do because the cases are pretty dingy after a lot of cleaning cycles.