A Pet Smart will charge 3 times more for a baby bp than a local breeder at a show. Because Petsmart would most likely be selling imported bp's they may have mites, and a bigger problem might be getting them to eat. These are the reasons that Petsmart isn't the vendor of choice.
That being said, if you already have a bp from Petsmart the world will not end. If you have no local reptile shows or local breeders a chain Pet store may be your only option.