Coffered ceilings do carry a modest cost value, but beware of low quotes from cheap contractors who have created a fast system which only benefits them. A true coffered will be crafted started with the layout and framing. It's vital to use quality wood, like poplar and stay away from woods like pine or mdf. A professional contractor will use techniques including back stapling and screwing in order to maintain a tight miter. Low end contractors will simply miter or cope together which will lead to splits, cracks and warping. Coffered Ceilings typically range $6k-12k or more.