I'd be willing to stick my neck out and say I've rarely been much impressed by the grain on any of the Dunhills I've seen in photos, including those breaking the 1000 bucks/quid/yoyos mark. Then again I still have a noob's glass eye for these things.
I would ask for better pictures. From what I can see, for the money, that set looks totally underwhelming IMHO. I went and looked at the bigger pictures and I'm just not that impressed for Dunhills. They just don't pop for me.
The buyer is obviously going after a premium for an unsmoked set. I don't see anything extraordinary about them. Certainly not $15,000 worth. But for someone who wants "pride of ownership" these might have appeal.
I can't imagine that set going for $15K, but you never know. For something in this price range you would like to see it coming from one of the most trusted of eBay pipe sellers.
Coopersark awhile back sold on Ebay a boxed set of Dunhill pipes. I wonder if this might be the same set. If I recall the final price was greater than 10k. It might have been 15k.