You gotta get the ones with the blue around their nostrils, not the pink/purple color. The blue-nostriled ones are the males, and the males love to chat.
What makes this difficult is that they ALL have pinkish nostrils when they are babies, but that's when you need to buy them if you want them to bond with you (well, more easily). So you basically have to take a guess if the pink is more bluish. I bought a parakeet a few months back (Humbert Humbird) and I'm -still- not sure if he's a boy or not.