I use cat litter pans for my bunnies. I ensure they are short enough so the bunnies can easily walk/hop into them. They are also relatively cheaper than the rabbit-branded ones. The other reason for this is because, my rabbits enjoy laying in their litter boxes. So I want to make sure they have enough room to do that.
You will see there are a lot of litter and bedding options. I stay away from the shredded bedding/litter as all it does is make a mess and get stuck to my buns feet and bums.
I get the pellet paper litter. It’s inexpensive and less messy.
I do not recommend the wood-shaving bedding as some buns have allergies to this and will begin to sneeze a lot.
Some of my friends have access to shredded paper, or have a paper shredder. They will use the shredded paper as litter. Newspaper is another good one that some people use to cut costs.