Guinea pig bedding question!

I have three piggies (Henry, Elvis and Mo) and I was wondering what other guinea pig people used for bedding. I usually use CareFresh but it is pretty expensive for three cages. I "freshen" Henry and Mo's cages almost daily and Elvis's every couple of days (Elvis is a lot cleaner than the boyz) and clean thoroughly every week, sometimes less. But what do you guys do? Isn't there something I can use so I don't have to use so much bedding, I think I make a trip to the petstore every week now to get more stuff.

I use kiln dried pine.,

I know many people who use Yesterday's News, and it is supposed to be cheaper.:)