If your not into building like myself or my DH, you could try hiring a local handy man to do it. Get some plans or ideas and have him build what you want. I had a kid from a high school build ours over the summer. He did a great job. Or if you watching your budget, try Craigs List. Sometimes they have old sheds you can buy and convert into a coop pretty easy.
Both gryeyes and swimmer's ideas are seconded by me. I have not found any prefab coops that I like. Usually they are a lot more flimsy than they look in the picture and what they state as the chicken capacity of the coop is not usually based on 4 feet of space per chicken. The Coops book is excellent for anyone who thinks they can't build. I know because that is what I thought before I got the book and I got the courage to build the large walk in coop by myself. DH and I did have the tools on hand though so if you do not want to build it yourself, go with swimmer's idea. Find a plan that you really like and have it built better than anthing you could buy on line.