I needed simple birdhouse plans I could use to build it with my kids. I changed a few things about your plans but not too much. I had a few wooden planks from other projects so I spend no money on this. If I have to make an estimate, I would say the birdhouse requires about 5 $ in materials. I will nails the wooden birdhouse to a tree in my backyard and I hope some singing birds will move there. Thank you for the work you do with the site.