You're thinkin too big. For a home breeder, especially the first time for commercial profit. Tanganyikan shell dwellers are small, yet fetch a good price. In the south DFW area, I could dump 1/4" for $15 a piece. Be careful to know that high shelf price doesn't mean you'll get that, the LFS has to get some change in their pockets too, on top of the overhead they'll spend keeping them.
At least look into the shell dwellers, in a long flat tank you could set up tons of breeding harems. Around here a good shell dweller (n. brevis/n. ocellatis) will go for like $40 a piece (more commonly 25-30). They are tricky to get breeding, but once they do they won't stop. Their fry yields are medium size (between 50 and 100 per drop for experienced pairs), plus the minimum tank a proven harem needs is a 10g.
Just some food for thought.