Welcome. I'm glad you are considering building your own! If this old biddy can build coops and tractors and green house, it's well within the capabilities of any one who has the desire and motivation! You will not be at all disappointed in your end product when you compare it to a pre-fab.
I suggest that you look at the Wood's open air style coop. These things are awesome, and appropriate for any climate. Plan on AT LEAST 4 s.f./bird in your coop, and leave room for more birds.
Other things to consider: Deep litter management will make "cleaning the coop and buying shavings" a thing of the past. You can do so in both coop and run. Birds who live on deep litter have healthier immune systems, better feed conversion rates, improved viability, and they are much more content b/c they have a job to do. The greatest advantage is that you will have beautiful black fragrant compost at your disposal without having to work at it, and your coop/run will never stink.
Other topics to look at:
Fermented feed. There is a faq how and why in my signature. This will improve bird's immune systems, and your feed conversion rate.
Build your own incubator. Check out Rush Lane Poultry for his excellent how to videos.
Finally, if you put your general location in your profile, it will help folks to give climate appropriate feed back/advice.
Be sure to check out your state thread.