Saving a Bundle on kitty litter

We have four large cats and use shredded paper as litter to save us money. The cats don't mind as long as they have a little bit of granular cat litter on top and litter liners underneath.  They have adjusted to the paper littler very well.  We shred the flyers, newspapers, and unwanted letter and generate our own litter.  In the past I used to get a professional shredding company to shred paper for me.  It cost $35 for 100 pounds. Today, my husband and I each have a shredder and use it for the cats.