[Sadden]

Straight from hcm's site.

In order to get the same humidity buffering benefit from kitty litter as from HCM beads, a person would need to use 9 to 14 pounds of kitty litter as compared to one pound of HCM beads. At $50 for a pound of HCM beads and $28 for 14 pounds of kitty litter, it appears at first to be a "value". The problem is, in order for the Kitty litter to work as well as one pound of HCM beads, it needs to be arranged so as to provide 910 square inches of surface area as opposed to 65 square inches of surface area for HCM beads. Are you willing to spare that kind of space in your humidor?
Even at that rate, the kitty litter is far slower reactively than are HCM beads. They can handle the buffering and provide the volume needed, but they take much longer to recover the RH of the conditioned space.