Try your local pet stores, walmart, pet supplies plus, some superstores and grocery stores too if you just want a pet. (Petsmart/petco do have really good selection usually compared to other places.)
If you want to breed them, post in the wanted forum here for what you are looking for exactly and someone might be able to point you to a breeder who might be able to help you.
You didn't really provide too many details here in your post as to what you are looking for. :D Keep in mind shipping is going to cost at LEAST $15 if you have a fish shipped to you. It might be more depending on the type of shipping + cost of fish. (Not sure what you have read yet here, sorry if you know about shipping charges locally.)
BTW welcome to the forum! :D
Betta Fish are like potato chips, it's hard to have just one!
Arm yourself with knowledge. Consider advise. Make informed decisions.