I swear by Petland Discounts I live in the SI, NY area and have gotten very good bettas and fish in general from their local stores. I posted a pic of my latest purchase check out Meet Mr. Pips post and good luck!
Beware, Pet... does not sell real halfmoons, only deltas marked up. Real halfmoons have to have 180 degrees and I ahve never seen one at the big box store myself.
I got mine at Wal-Mart. *L* I don't know what type of budget you are working on, but you might try bettatalk.com She is a breeder, has been doing it for years, her shipping is pretty reasonable, and she has some betta's to die for.
have you tried asking a local pet store to order the color and kind of betta you want? if you have a mom and pop fish store they are really helpful at ordering something if you ask.