Correct me if I'm wrong, but I think it's the only time an Apple product cost more than the same configuration in another color. (Except for the Apple Watch, but they are made from different materials)
The Jet black glossy iPhone 7 wasn't available in the cheapest configuration, but it cost the same as the other colors at the configurations it was available in.
I think the black glossy iPhone was one of the most beautiful phones Apple has built. It was the closest they got to a truly seamless, monolithic phone. And it didn't have a stupid glass back that always breaks!