Some of the more rare Africans do go for a nice price. The problem is that they need time to mature & pair, which means a rather large tank.
Best thing to do is research your area. What sells well in one area often times won't move in another. Trying to make a living off of breeding fish requires a large investment in equipment, as well as time. Often the market swings up & down, what sell really well now is sometimes impossible to sell in a year.
You can make your hobby self sustaining without too much trouble. After you've done some research, buy used equipment, and build as much of what you need yourself. Keep a log, once you get past 6 or 8 tanks, you won't remember details from 6 months ago. Those details can be important.