Warning: Spoiler! (Click to show)
Sorry, I am going to weigh in on the other side from what's been said above. It's unfortunate that such a beautiful pair of boots arrived with that scratch, but it's really a minor surface scuff. From the photo, it looks like it is just the wax on the surface of the shoe and will be almost gone with five minutes of brushing.
If you don't feel like you want to keep them with the scratch, however, then just return them. Personally, I would not ask the retailer for a price adjustment because of it -- nor do I think the retailer should give you one. It looks like a scratch caused by one of the little brass bobbles that come on the dust bags, and easily could have happened during shipping (and thus could not have been seen by the retailer before shipping).