I get your point, livebearers are so easy to breed that everyone gives it a go taking the market away from you. I know of people in this country that have bred pencilfish in tanks (Beckfords, marginatus and another I think) but I don't know how easy it is to get quality breeding stock. The water needs to be soft as far as I can recall. I suppose, again if it were me, I would work out what I liked first as there's no point breeding a fish you don't enjoy keeping, then find out what kind of market there is for them. If you went for the smaller fish, eg pencils, tetra etc it would give you more room for different species than larger cichlids as they would need more space and would be more of a specialism I suppose. I would guess that they'd need 1 tank per pair and more growing out space than the smaller fish. I don't know if that's a consideration? Being in the UK I'm afraid I can't ofer any suggestions regarding ponds as they'd freeze to death here!