Around here, walmart is the only store like that. There is a kmart but its small and they tend not to carry too much of what I need. We have a small pet store but its stock is rather low most of the time. The joys of being in a small town. Luckily I have never seen anything like that here at the walmarts here. They tend to keep at least twenty bettas in stock maybe less every time I wonder into the fish section for something.
I brought Spot there, he's a healthy happy fish. Its going on about week since I had him. If there wasn't a walmart here, I most likely would have a betta again until I made another trip to Erie which tends to be out of the way most of time.
I am sorry you had to go through something like that.