Before you go creating all those fry, remember that each guppy female can have 30+ babies every 6 weeks. If you get two females, that is 60 new fish in the first month alone, you can do the math for the months after that. Can you house 60 new fish? Do you want 60 guppies? That is an awful lot of fish tanks for all those fish. Don't count on your fish store buying them from you, they will either pay you next to nothing for them, just give you store credit, or take the fry to sell as feeder fish as a "favor" to you for taking them off your hands.