Price is usually about rarity. Fit and finish also come into play, and some will pay more for "luxury" brands like Dunhill.
Brand reputation is important because there is always the risk of wasting good money on a pipe which does not smoke well.
I love the look of dense briar burl grain and birdseye as it plays across the curving surface of a pipe.
I am willing to pay a premium for a well-grained pipe.
When smoking a pipe, the darn thing is right there in front of your nose so you kinda have to look at it. Therefore it should be pleasing to your eye.
A flawless, smooth, flame grain pipe from a reputable manufacturer commands the highest price. Personally, I have no problem with a few small pits and fills, as long as the grain is good. And "good grain" to me does not necessary mean vertical, or even straight--"interesting" is my preference.