I have suspicion that the guppies carried by majority of the 'chain' stores are transhipped through Asia, along with their Angelfish.. A recent Q&A in TFH leads me to believe that their is a viral issue with a majority of these 2 species that is widespread and brought in from the Orient.. Centrally filtrated system with shared waters passes this disease, and it is believed to be un-curable.
I would highly reccomend seeking out quality stock through local breeders and LFS, or atleast have a rigirous quarantine process with the use of Acriflavine and Saltwater baths.
Good luck broz!