Impatiens flanaganae is another one of those "rare" plants on ebay, but it is easy to grow, less easy to flower well. I may have been the person to introduce it into the USA when I brought a cutting back from South Africa to the New York Botanic Garden in the early 90's. There are some other plants I also brought back that I now see in occasional commerce, though it is always possible others also brought them in. Among those that come immediately to mind are Plectranthus hillardiae, another Plectranthus species with much larger succulent and aromatic leaves later introduced by ISI at Huntington from material I brought to California and Brilliantaisia nitens (possibly misidentified as to species), a huge growing purple flowered Acanthaceae I got from a wildflower nursery in SA that said they got it from Zimbabwe.
Impatiens flanaganae is an endangered species in its native habitat near Port St Johns in South Africa, but is grown by at least some nurseries in SA, for that is where my material came from. It produces tons of red potato like tubers by which it survives the winter after it dies back. They can be left dry in the pot until they sprout in late winter or spring, or if taken out of soil they are best kept in ziplocks in the fridge or they will dessicate. It will flower in mid to late summer here in NY, but often suffers from broad mites which damage the flowers and curl the foliage, plus it will drop seed pods and buds if a really hot spell comes along. This year was its best so far, lots of flowers and even a handful of seeds were obtained. Lime sulfer eliminates the mites, but can be used only when it is really cool or the foliage will fall off. I used it on my two plants of I. tinctoria in September when the mites were too abundant, its close cousin which I was thrilled to obtain from a specialist grower after two failed earlier attempts to grow it from cuttings. I got rid of the mites, after the lime sulfer caused some leaf drop, and now the tinctoria plants are in their winter home in my classroom, growing well with good new foliage. It doesn't appear that I. tinctoria has an obligate dormancy so far, but I. flanaganae does, and is fast asleep already in two large pots in a cold hallway.