I would just go get some feeder guppies from your lfs, around me they are 6 for $1, they are usually just under breeding size. For $10 bucks I have 60 guppies ready to breed in about a month, feeder guppies IME are more hardy than fancy guppy's which have a tendency to have higher mortality rates during birth.
My question is can guppies give birth in salt water? I know you can adjust adults to full saltwater, but can they get pregnant and give birth to healthy babies in full salt water? Wanting to know for possible salt water feeders.