BUILD YOUR OWN
If you have a spare weekend, you could knock together a very basic composting toilet in your garage using little more than a few pieces of plywood or shutterply to create a basic box shape (naturally, it will need an appropriately large hole cut out of the top), a toilet seat and a large bucket. Add a suitable enclosure (an unused tool shed might work; just add a ventilation pipe) and a bag of sawdust, and off you go.
A high-set seat will accommodate a larger waste receptacle, so you may want to build a bigger box and attach one or two steps for easy access to the seat. Estimated cost: about R300. If you have scrap timber in the garage, the cost may come down to almost zero.
If you’re not squeamish, aesthetics is not an issue, and your yen is for simplicity, you could forgo the box and settle for a toilet seat fixed to a large bucket or unwanted commode, with a bag of sawdust on the side. When the bucket is full, transfer it to another receptacle for the next stage of the composting process, and start over. Yes, it could be that easy.
If, however, you have the patience to wait for an Amazon delivery from the United States, consider buying a profusely illustrated and informative volume called The HumanureHandbook:AGuideto CompostingHumanManure by Joseph C Jenkins (it costs about R260 and yes, Amazon will ship it to South Africa). The book contains detailed plans that will speed you on your way. If you would prefer to go the online route, have a look at the Compost Junkie website for equally compelling step-by-step plans ( compostjunkie.com/compostingtoilet-plans.html).