I’ve priced this out…I think it’s better just to buy the premade mix of how much you need. By mixing your own you will probably need to purchase more than you actually need.
If you want to go with a bioactive planted Viv you want to create a substrate that drains well and does not hang on to moisture. Your plants roots will rot with potting soils. In the Cham Viv you want a mixture that dries and out very well and also does not hold moisture.
Mixing your own requires purchasing materials in fairly large quantities (orchid bark, hydroton/leca, leaf litter, sphagnum moss, coco fiber) For a planted Viv ABG Mix is what you want to create (developed by Atlanta Botanical Gardens) though ABG will also hang onto moisture.
There are vendors that sell mixed substrates so you can purchase what you need and not be left with unused portions of material.
I purchased a substrate package from NEHERP, which they make a chameleon Viv specific mix called NEHERP Version 2 Substrate mix. It is designed for lower humidity environments than ABG mix. NEHERP has kits that include drainage material and screen material cut for your tank size.
The BioDude also has a Viv substrate mix called Terra Firma. They claim it does not need a drainage layer.
You can also make mixes that are suitable for your clean up isopod cultures too.