I buy my Flowerhorns from Bill Berry. I got quite a few from a friend in Atlanta as well. I will dig up Bill's contact info for you if time permits.

You can also buy Flowerhorns overseas. It's really fun when they come in alive, and you don't have to hound someone to get your money back for shoddy shipping. When the fish come in dead, too bad for you. They're over there and you're over here. Nah nah.

Aquabid also has Flowerhorns but I have heard some horror stories where you buy the fish and suddenly it costs more or it's already been promised to someone else face to face. All sorts of stuff.

You're just lucky if you live in California because there are a lot of stores there with Flowerhorns.