Is there a setting for black and white printing from iOS?
There doesn't seem to be a way to do this natively.

Your options seem to be:


Get a black-and-white airprint printer.
Use a black-and-white, non-airprint printer with AirPrint Activator.
Use Epson's app which seems to let you print black-and-white photos.
Use HP's app which seems to let you choose these kind of settings.
Tell Apple you want this feature.