I would like to grow some Streptocarpus plants, but can-not find any source of seed, plants, or leaves for propagation.
You can buy leaves for propagation on eBay, but I might suggest you go to our Plantfinder page which will give you some useful overall information about Strpetocarpus along with a link in the 'Plant Marketplace' to a garden centre who will ship them anywhere in Australia. Here's the link to the page:-
https://www.gardensonline.com.au/GardenShed/PlantFinder/Show_1036.aspx