I built my coop in an existing building, close to the house, and I love it......
......still was spendy as I made a 6 sided 'envelope' to over-ensure that no predators would ever get inside the coop itself.
I would not recommend doing a composting DLM in a wooden floored coop as the floor may eventually compost away too. I used single sheet vinyl flooring and keep things bone dry inside to prevent any floor rot and reduce humidity, especially for winter.
Design can indeed produce throes as there are so many ways to do things, you've got all winter to decide and plan and draw and gather materials.