Hamster bedding help?

I really love carefresh paper based bedding, but now that I have Sonny, my new Syrian, I'm going to have to buy a lot more of it. Right not he's in a 10 gallon aquarium, but I feel it is much to small and need to upgrade it some how. Jojo, my other Syrian, is in a 20 gallon long, and that alone takes up a lot of bedding. Right now I used Carefresh natural. I suppose the colored ones are nice, but I never took an interest in them. I usually buy a 60 liter bag ( expanded) from my local pet stores for about $20, It lasts me at most 3-4 weeks. I know there are some alternatives, but I forgot what they were. Other bedding options I've heard of have been hazardous towards hamsters, so I would like to know what kind. Thanks guys :)