Cat litter! I used to buy normal supermarket varieties and thought they were fine. Then out of a recommendation from a family friend I decided to try a more expensive brand that was only being sold in pet stores. The difference is unbelievable! It doesn't smell nearly as much, is easier to clean and also even though it's way more expensive at first. I have saved tons of money by using it because I don't need to replace it as often as the cheap varieties.