CityDad, there are a few aquarium hobbyist that handle a few to the tune of about 5-7$ each plus shipping. I'm fortunate enough I've found a location about 2.5hrs from me where I have an endless supply now so as far as numbers I have not found any other source but they are widely distributed in the wild. As young, they are quite hard to identify. The adults are "almost" unmistakable.
I have not searched widely on the east coast, there may possibly be someone handling them but it's been a long, hard search.
