The BioDude and Josh's Frogs both sell bioactive kits. If you have a hydroponics store near you, you can find some great organic mixes and then add your own isopods and leaf litter. That's where I picked up my substrate.
The guys at the store asked me what I was growing (they assumed it was some type of cannabis) you should have seen the looks on their faces when I told them it was for a bioactive chameleon enclosure. ???