I have 6 with my betta and dont have any problems at all, my tank is also cycled. I have a tiny one in there too and thought my betta would eat him but he is still alive and kicking. They eat with the corys (wafers) and some times I found them trying to eat a whole betta pellet.
Ask them whether they have them or not. People usually by like 20 at a time because they are feeders. So, usually they are out of them. Try going on the day they restock (For the bettas, my pet smart restocks on friday) and in the morning. Most pet smart open at nine.