I'm commenting here to answer my own question in case someone else has this question because I stumbled across someone who has actually kept and sold Bengal Danio before, and they had some answers.
Apparently they are more expensive, typically between $10-15, because they require more time on infusora than other danio species. Additionally, they take a long time and a lot of care to color up, so people see a pale green/silver fish with nothing notable in a pet store for 5X the cost of a gold colored leopard and understandably ignore it.