So.... you get what you pay for.
I have always gone through breeders and will always go through breeders. Breeders have healthy stock (the known and respected breeders), they have cared for their snakes very well, and they are there for you after the sale.
I urge you to not support pet stores but instead support the breeders who work very hard to provide healthy animals so as to make your initial foray into boas a positive one.
Jimi has amazing snakes and my favorite boa is the one I purchased from him. No kidding. She is an amazing example of what a boa ought to be.
Pay more- get more. Pay less (pet store) and you run the risk of paying a lot more in vet bills and hassles...
Just my 2 cents.