Hi New Betta Guy!
Hikari is a very good food. Personally, I rank it third best, and third is NOT a bad number. PetCo keeps the Omega One Betta tablets (the ones I use) and NLS Betta pellets over in the actual fish food section, not the betta areas. It is entirely possible your store does not carry them at all, but check there next time you're in the area. The Omega Ones are the very first food on the top shelf from the left (I work at PetCo, so I have the fish food shelves about memorized). Its entirely possible your store didn't sell enough of them and they don't carry them, but that's where they would be if they do.
If they don't, Hikari is a very good food, and your betta will be quite healthy off it. I just don't use Hikari or NLS myself since they use Antarctic krill, and there are some serious overfishing problems of that krill that's leading to a decrease in the penguin population. Since penguins are the most superior animal in the world, I won't touch food with it.