If you go to a pet store, like say petco, you can get them for about 4-10$. They are a lot less likely to die on you if you get it at a place where they actually take better care of them. I don't know about the walmart you go to but at mine half the fish are dead and you never see anyone feed them so they just eat eachother. It's sad. Also bettas can be in pretty small tanks so you can pretty much get a tank anywhere for about 3$ and up. You can feed them any fish food really BUT if you get them special betta food their color stays a lot more vibrant and healthy. Which will be about 5$.