Again, it is not impossible to keep them, just unwise and expensive. The equipment alone being used in these pictures runs for $10,000+. This also appears to be some kind of research institution which may in fact be in Africa, based off of all the pictures of them in the wild and the...
This site just shows a few pictures. It doesn't say whether this is a zoo or private keeper. You also don't know where this person is located and how much they spent on the enclosures and tortoises nor how long the tortoises lived or are living. Just because there are a few pictures of something...
The wild tortoises that do get pyramided are most often the ones that live near human settlements and eat refuse and food waste. It is not due to their natural diet.
They have two mata mata pages, one that just says mata mata and another that says mata mata (hatchlings). There is still one available on the hatchling page.
They are an excellent pet store. A while ago they had a pair of Galapagos torts for sale. They called them the 60,000 dollar lawn mowers. Turtlesource.com has some captive bred mata mata babies for sale at $450 each.
Pet Kingdom, a very good exotic pet store in San Diego. I am afraid that they do not sell online. Their selection is great, lots of turtles and tortoises.