I have guppies galore :P(they were my first fish of my own)
I started with 2 male and 2 female adult guppies...ended up with more than 50 fry.
Most of the fry have grown, had babies of there own, and died now.
I still have a 10 gal tank full of guppies. My littlest bro raised 5 guppy fry that i gave to him and they recently have had guppy fry of there own.
They are'nt called the million fish for nothin lol
If you want fry just buy a fat female guppy that wen sold was kept with male guppies. Chances are she is pregnant and will drop fry in a couple of weeks to a month.