A lens with a focal length of 10 mm has been a large opening angle. The result is that the hood has a considerable diameter and still u. U. the image can affect. Intensity light come therefore increasingly not from the opposite direction (keyword "Gegenlichblende"), but especially from the peripheral regions, or even from the side. Precisely this incident or scattered light is therefore reduced. The uses for this lens hood hold So in contrast to longer focal lengths within limits.
Going back to the initial question: A lower price would certainly be done, because the one experiences but for the rather simple plastic part as disproportionate.