Hey Huzi,
Where about do you stay?
The lifestyle centre in randpark ridge caters for your needs

I just got myself a few "Tom thumbs" which are a variety of different plants but specifically selected for terrarium use. There is a plaque over them that states "ideal for terrariums"
The lifestyle pet shop sells cork bark sheets @ R60 per kg.
I also posted a thread on how to make your own tubes out of cork bark. It involves soaking the bark in boiling water for about 30 minutes and then wrapping the now softened cork around a bottle (500ml worked best for me) and tying it with string or elastic and then leaving it to dry over night.
I had great results with this method.