What cover is cheaper to create?

Just found a good question on a linkedin group discusion.
The question was: "It should be cheaper to create a book cover for an ebook?"
There were two answers saying "Definitely yes" (well .. with some variations).
My opinion was the other way.
I truly think that you have to put much more efort in designing an ebook cover if you are looking for a great end product. Why? Becouse you have to consider the size of the screen, the colour reproduction capabilities, the impact of the device color and so many other similar factors.
Considering the fact that you don't have to wory to much about colours and how the printing house will reproduce them on paper in a modern cover designer shop I think there is no need to insist in proving my point.