I do not personally buy anything from petco. even though some of the stores are tolerable, tolerable is not what I look for in a pet store. I look for reptiles specialists who have perfectly clean and correct cages, healthy feeding herps, and are willing to tell you the breeders they buy from. If a store will not tell which breeder it uses, you can bet that their snakes are wild-caught and probably tick-infested.
Of all the sources I have used for Bp purchasing, the best method I've found was ordering right from a reputable breeder. Your snake comes in the mail a day or two after you order, and you get the security of knowing its sex, date of birth, and parasite-free status (if you go with a reputable breeder.) I got my newest Bp frrom Alex Hue Reptiles, and she's healthy and perfect!