It won't just be the one part, it'll be a whole mech. with regulators and such that they want to sell him, plus labour.
Its easier to google/eBay the particular part number which can be found on ETKA or ETOS and buy the individual part, budget one set of torx drivers, some fasteners and an afternoon.
I've even known some people buy entire convertible roofs with frames, and folding roofs with motors and glass, cut off scrap cars and shipped out on pallets. But I berate everyone who goes to a dealership the same way; if you're dumb enough to go to the robbers, you're going to get robbed.