I got a 4cu foot bag at tractor supply store for like $15 I think. I got it back in may and have only used like maybe 1/5 of the bag and I have 14 balls. It's in the small animals section. It's like the curls of Aspen too not the little shreds or chips, I like it a lot. I used newspaper before and while newspaper worked and was free, I like the looks of the Aspen a lot more and it has some benefits so that minimum cost is justified for me. I'd imagine that one bag will last me at least 6 months.