Do you have a specific brand you prefer? Just buy whatever is on sale? We used to get the Petco refillable litter, but they changed the formula or something recently. Not only did the cost go up, but they no longer include the scented crystal things - those are now sold separately at $5/bag and you’d need 3-4 of them for what used to be included. Plus it no longer clumps. We want to keep the kitties happy, and since it doesn’t clump and smells, they are not happy and neither are we.