[zdragnar]

Animal bedding (pine shavings, essentially) works wonders, and is very inexpensive.

[Scoundreller]

wood pellets, but buy them from the hardware store for a fraction of the price of what the pet store sells them for. Dunno about the horse store.

[zdragnar]

You're right about getting it from a hardware store, but the bedding is cheaper and works much better than pellets:

https://www.menards.com/main/pet-wildlife/rabbit-hutches-chi...