Those are very common here so not sure what's rare over there. I would start looking Trimacs, Festae, Honduran Red Points, Vieja , Blackbelts, and some Buti's.
I've got a breeding pair of oscars and HRP's, with 7 Trimacs and 11 Festae, and 5 Jags in grow out tanks. Waiting for the pair, since Festae and Trimacs will command some coin.
If your looking to make money it's not in SA/CA
, it's African peacocks here. I can sell peacocks all day due to their color and size by the heavy hitters down south require large tank which cuts the aquarist world by 70%.
And it your really in it money then just stop because youll hate every miniute of it. I truly enjoy fish, in fish tanks, at the lake in my boats livewell, and after along day at the lake in my frying pan for shore lunch.