Well the article DID say "most newly released books" or whatever. I believe the 12-14 price is for novels that only exist in hardcover. And as to the additional cost, you're not paying for materials. Do you really think a cardboard case and glossy jacket cost the company 15-20 dollars more on a regular hardcover? No. It's a matter of economics, is all. Think of it in movie terms. When a movie first comes out you pay 10 bucks to see it in a theater. It's in demand, people want it, theaters/studios can charge more. Then when people don't want it as much, licensing fees go down, dollar theaters pick it up, etc.

Things always cost more when they're new. As they get less desirable, the price goes down, and is not always (or even usually) related to cost of materials. We're seeing the same thing here.