I'll keep my eyes open for World's Best Cat Litter. How expensive is it?

My little boy, Norman, is a very tidy little boy. He and his sister, Isabelle, share a hooded box and prefer Tidy Cat (multiple cat formula - non-clumping), but despite a sisal mat, those little pebbles find their way all over the house. I don't scoop, but clean their box every other day. Norman insists upon it.

I do know I give a hearty thumbs-down to Johnny Cat. The kids hate it and it is filled with dust.