I bought my coop from a guy that had an
ebay store & craigslist listing. I needed a coop and didn't have time to build one. You get what you pay for.... My coop is okay, but there are issues. I had to add 'rungs' to the chicken door so that my girls could get in and out of the coop. I also had to change the hooks for the vent, egg door, and chicken door as they were cheap and wouldn't stay locked. The lumber used isn't pressure treated - so I'll have to deal with that in a few years. The siding of the coop is interior paneling - so I have to deal with that this summer. I also had to caulk around the doors and windows because they leaked every time it rained.
All in all, my girls don't care. They are warm and dry, have a place to stay safe, and several nest boxes to lay eggs.
When it is time for me to enlarge my coop, I'll build one with the correct materials. Good luck with your coop. I would ask the seller questions about the materials used and how it was built. You may find that for a few more dollars or extra time searching for materials that you can build your own coop vs. buying one. I checked out a few chicken coop books from my library-and I like Chicken coops for Dummies-it gives material and cut lists for several different coops, plus the building instructions.