From reviews on here and posts on different threads, it seems the pre made & coops from kits, are cutesy but lack substance. The don't hold up to weather or predator attacks. The number of birds they can house is grossly over exaggerated. Sometimes you can find a decent coop on Craig's list.
There are many styles and sizes etc. on the coops section above, some with detailed plans. Do you have any one with carpentry skills? They could probably whip one up that would be less costly and last much longer. My sister had remodeling done by a shop teacher from a high school in the area. He did projects when school was out for the summer.
Some folks trick out a storage building, garage etc. If you plan to just keep a small flock, you may want to view the chicken tractors,. which are portable coops you can move around the yard.