A copper roof is perhaps the ultimate luxury—especially now, when scrap alone sells for as much as $3 per pound. Capping a new bay window in copper typically runs $2,500 to $3,500. But you can knock up to $1,000 off that by using a prefab roof. Order them through window retailers and online at decoroof.com and proofroof.com. You get the same 16-ounce material as with a custom job; the savings are in the labor, because a prefab system can be installed by a general contractor or window installer in about an hour. It could take a specialty roofer or metalsmith more than a day to shape, cut, and hammer individual copper sheets or shingles into place.