I would ask them if they would let you have that crestie as a rescue for free. Paying money is indeed supporting them, that's why I would advise against it. It gives them reasons to keep doing what they're doing. They can pretend to want to make changes, but with money coming in, corporations have little incentives to make changes. Their sole purpose is to make money, so the only way they would change is if money stops coming in.
I will say that these stores (petco/petsmart) are often independently owned franchises, so you can find a store owned by a good owner with caring staff. But too often you find stores that just don't care much about the animal's well-being, and they hire minimum wage employees with no knowledge to save money. The local petco here used to be fairly well run. But the ownership changed hands not long ago, I saw their quality went way down, they started not staffing enough people, and the place is a mess now. I stopped going there for good since a year ago.
These stores have millions of customers and I don't see any change happening as for the care of their animals. Like I said, as horrible as it is, they don't care, they need to make money and they don't care how they do it. It's as if these animals aren't living and breathing creatures and just "inventory". 
