well i use cocosoft coconut substrate and its VERY cheap, a 5 dollar bag will last a while because you just takeout the small patches that are soiled and replace, they hold moisture very well, i have a 30 gal, and you dont need to line the bottom just like under the hides, or sparatically around the rack, basically just douse the husk before you put it in and it keeps moisture well, get a spray bottle and mist once a day and you should be great