Frank at guppyalturnative is great and the fish first class. You can also find breeders on Aquabid. Don't buy that junk at the pet store. They are likely shipped in from asia and good only knows what they may bring with them.
Pennyls9332 is right that just about any shop will have fancy guppies. Those are perfectly fine, but like any other fish you should quarantine just to be certain. Really no need to buy online unless you want certain forms. If online buying is something you want to do then you're best suited looking for a source closer to home than the US.
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