Hi Amy
There are lots of different types of bedding available. If you are just wanting it for your litter tray a lot of people just use newspaper and then pop hay on top, but there are quite a few different other products that can also be used such as:-
Megasorb - comes in 80 litre sacks
Aubiose - comes in 20-25 kilo bales
Bed O linum - flax bedding only needs changing on average every 2 weeks, available in 12.5 and 35 litre bags
Carefresh
Shredded Paper
Wood Pellet Cat litter
etc etc