Amazon offers the Arm & Hammer Odor Busterz Balls 3-Pack for $5.82 with free shipping for Prime members. (Home Depot charges the same via in-store pickup). That's the lowest price we could find by a buck. They're filled with odor-eliminating baking soda and Arm & Hammer's Clean Burst fresh scent, which purportedly eliminates odors for up to 60 days.