Long before the BP morph explosion hit they were routinely used as feeder snakes for eastern indigoes and king cobras. Also, a feeder BP isn't $20, usually males are sold off in large lots by the big breeders for a few bucks apiece.
Also, where do you think the kinked babies and stillborn babies go? There's a king cobra keeper near me who will pay for kinked babies and stills to feed to his cobra. Better that they get fed off than thrown in the trash.