Our local Farm Supply Store happened to mention that many of their customers use Non-Medicated (important) chick starter (yes baby chicken feed) as kitty litter. We tried it and it works super well. It even clumps a bit, is a little less dusty and comes in a BIG bag for about $15 CD. We have one cat that likes to eat a bit but it will not hurt them. We transitioned by blending it into clumping clay litter to start and phased out the clay fairly quickly.