Same. What you can buy locally is all Chinese 125ccm or 150ccm. And there are a few Honda 250ccm dirtbikes around too.
There is a KTM shop in Nairobi but that one is heaps expensive.

The Chinese ones are not too bad. Although they fall apart quite easily they can be repaired super cheaply in local shops everywhere. We bought one in Tanzania and did 5000km with it without major issues. Price of a brand new one is less than $1000 for the 'big' 150ccm model. Second hand ones are highly sought after so it's easy selling the bike after your tour.

Also looking to buy a cheap bike in Africa
 

Hello, I'm adding to this post because I have a friend who is also looking to pick up a bike in Africa instead of shipping his BMW 1150GS. He is hoping on finding something for a couple thousand $$ that he won't mind trashing. We are still not sure where or when the trip will start. Thinking either Djibouti around March or April, or South Africa around the same time.

Anyone out there wanting to sell, or know how to pick up a bike?