I used to use Tidy Cats crystals, which work really well. A jug at Wal-Mart costs about $7-$8 and lasts for as long as a month for one cat. My cats didn't seem to mind the crystal stones, but they can be hard on people feet if your cats are like mine and like to "throw" litter out of the box while digging.
I found something else last week at my local pet food supply store, so I think I'll be switching over. It's called Feline Fresh, is made of pine, and comes in two different options - pellets and a sawdust like material that is scoopable. I got the smaller bag (6 lbs) to try it out and that was about $5. So far, it's been working quite well. I've scooped the box about twice a day since then, but it doesn't look as though the litter level has gone down that much. I only used half the bag to fill the box, too. You can also get it in a 17 lb bag, which at my pet supply store was about $12. The webpage for the company also lists other products they have, as well. http://www.planetwiseproducts.com/