Hi, have you considered options for different types of coops to save on building costs? Hoop coops generally are less expensive, or some people convert plastic sheds into coops. Repurposing materials (like pallets for wood or re-doing kid's play houses for the structure) is a good way of cutting down on costs too.
Here's a link to the Coops articles, scrolling through those may give you some ideas to use for your own: chicken-coops.12
Best wishes!