Not gonna make any money unless you breed one of the more expensive species like Discus, Festae, EBJD etc, and even then you might not make much. People won't pay unless you can prove the quality of your stock, you can't just breed Petsmart mutts and then try to sell the fry. A baby festae from a high quality wild caught pair can be sold for $7 or 8 a piece at 1", but when you add the time, housing, food, maintenance, the cost of the parents (WC pair go for $300 and up. Some people want $300 for a single adult fish) and all the work you have to do in order to sell, pack and ship all of em, well... you get the idea. Then there are all the risks of breeding expensive fish (male killing the female, pair eating the fry, fish dying during shipments, etc, etc).
Then there's the competition. At the moment Festae are being bred by like 50 people on MFK alone, and Discus well... there's a whole industry dedicated to that. Basically there's no $ business in breeding Cichlids unless you plan to do it on a big scale (i.e. a fish farm or a small fish store).
Convicts are worthless as are most other common species JD, GT, Oscar, etc. They're so readily available that people don't even consider paying for shipping to get em for free.
But I'm talking about a decent amount of money here. If you just meant $50 bucks every now and then to buy cigarettes, there's a lot of species u can try. Just look for those with high demand.
hence my recommendation for African cichlids. There are more popular species there than I can count and many regions have deficiencies in one area or another you can talk to your local retailers and look on craigs list see what is there then fill in the blanks and start breeding what isn't. Overhead for even the most expensive africans is so much less than most of the larger SA fish IMHO you could pick a strain of frontosa or Gibberosa. Those being probably one of if the the most expensive fish to keep and breed from the african great lakes. Also the cost of wild africans is way less than wild south Americans for whatever reasons.
Because of the large selection of africans there is not much in the way of direct competition between breeders. You could breed 12 different kinds of fish and not overlap with many of the other breeders so no direct competition. Its great! As for overhead the smaller average size does seem to make the fish more profitable as well. If you want to go SA I would recommend doing Pbass since they are still underserved in many areas. A standard mono fry goes for 30-50 by me at 1"-3" in size.