There are some natural, more "edible"

litters. World's Best Cat Litter is corn...but it also has the world's highest price. Chicken feed is essentially the same as world's best....but much cheaper.
EDIT: But I think you need to be careful picking the chicken feed, if the cat's really going to eat it...I think some of those could have antibiotics and weird stuff in them. I forgot that part. Some do not, though.
Or there's Swheat Scoop which is wheat. There are a few more...those are the first that come to mind.