Your not going to see a green betta at a petstore. Even the Thai and US fish breeders who are breeding on massive scales would pull a fish like that out of their pet store shipments... although someone on my dog forum found a male giant PK at a petstore.. so I guess you never know.
I found one that was charcoal AND red at a specialty breeder's. And my Flair is a sort of reddish-orange.
So wait, the breeders sell all the prettier/more finely bred ones online and send all the less special-looking bettas to stores? Maybe that's just business, but it doesn't seem fair to me.
Most of the fish at petstores come from fish mills... people who breed fish on a large scale for the purpose of sending them to pet stores. There is a major on in Wisconsin or Minnesota.. something like that. And the others are in asia.. Thailand, Indonesia, etc.
Hobbyist breeders who are breeding for form an figure don't let their fish go to pet stores unless they have an arrangement worked out with a local store.