Hi mate, here's the way I see it;
Platies and swordtails can cross breed to produce fertile offspring.
Guppies and Endlers can cross breed to produce infertile offspring. The guy who posted about the guppy with a swordtail? This is something which some of the endlers possess and so it is most likely that the "sword" guppies you saw were in fact guppy/endler crosses.
Mollies can not cross breed naturally with any other livebearer.
Guppies can not cross breed with mollies or with platies naturally.
Yes platy - mollly crosses and guppy platy crosses have been produced but this is not natural, this is through scientists extracting the sperm from the male, before reinserting it into unfertilised eggs. Obviously this isn't going to take place in your fish tank
So I'm sorry you won't be making any mega bucks, besides hybrids aren't too popular anyway