The black one is a 350.15 WITHOUT display. Grey and white are 350.35 with display.
Galaxus is making a mess of things here.

Unfortunately, I cannot answer this question. I would ask De Longhi directly.

I suspect a migration background, white is valued more highly... No kidding, no one knows for sure. My real guesses are dynamic prices from Digitec or just what is more in demand. If more people want a white machine, then it will be more expensive because the black version will be in stock longer. If they lower the price a little for black, they will get rid of it sooner.