If you've got a lot of hackberry, you are set since it is one of those woods you can use for multiple designs and it will keep you interested. I used to live in Nigeria for a year with family friends and if I could go back, I'd be buying ebony. Ebony is an amazing bow wood. As is African Blackwood. Problem is that it is an ecological disaster at the moment the way they have over harvested it illegally. Still, if you've got some around, you could stave up a straight limb and billet it without doing any real damage to the tree. Zebra wood will make a bow as well. I live in Taiwan now and over the last 8 years have been trying just about any species of tree that seems promising. That and I recruited the help of a university botany professor to ID trees for me. It has expanded a lot of local knowledge in the aboriginal community I shoot with as to what will make a bow. They tend to just stick to what they've always used and not branch out. So, I think if you just keep your eyes open and research tree species in your area, you will most likely be in for a real adventure for years to come and help expand the online community's knowledge about usable South African bow-wood.