I can't seem to find them anywhere: I tried Google, my favorite fruit sites, and have only found one place in England that sells Natal Plums.
Anyone have any ideas?
Have you asked at a local nursery? They are pretty ubiquitous here in SoCal as commercial landscape plantings in parking lots, office building planters etc. West Valley Nursery in Tarzana has a dwarf form. I haven't been able to locate any culinary selections either, if that's what you're looking for. But Natal Plum we have here in abundance.