Sorry that I forgot to ad this to my post above (about the sawdust), had a bad weekend and well, was tired when I wrote that. My bad.
Yes, sawdust is not good for the lungs but, the problem is in a workshop where you have saw/sander throwing it into the air at high speed (and also some exotic/expensive types of wood are even toxic.) But adding it to cat litter, in small amounts, will not create the same hazard. I've had more of a problem with the dust from the clumping litter than I have had from anything else.
My reason for adding that info it is the cost and the fact that the litter should still clump with a little sawdust added.
But, from a vet I knew for years btw, clean, shredded paper (think confetti or the like) can be used as cat litter and, if changed when needed it does work well. This is what he used/recommended for some cats after surgeries because it can be gotten cheap, is clean for the cat dust wise and so on...
But as with all things in life, your mileage may vary.