Instead of buying a treat ball, I use an empty cardboard salt canister. I don't know what you buy your salt in over there, but ours comes in carboard canisters with a metal pourspout. When we empty one, I just pull off the metal spout and pour a serving of pellets in the little opening. The buns go crazy rolling it around, kicking it, picking it up and shaking it and chucking it about to get the pellets out. It takes a while, keeps them busy and gives them a workout. Eventually they chew through it enough that it needs replaced, but it can be reused for a good number of days if your buns aren't big chewers.