I think it really depends on the situation.

If it's a store that has lots of snakes then a rescue just isn't feasible.

I bought a rescue because it was a special case. It was the only BP is the whole store. They generally don't carry them. It was sold to them by someone who couldn't take care of it anymore.

They also didn't know what they really had and sold it much less than it would be on anyone's web site. It's a big beautiful pastel male. So I had multiple motivations to buy this animal. Being a rescue was just the big kicker.