The big part is getting the ribs bent. I think I will be setting up some kits and fixtures/tutorials for making tube bending equipment. A 20'x10' tunnel like mine could be built for around $320 using the materials from local big box stores. This company sells kits for tunnels for a decent cost as well as tons of great accessories for market gardeners as well. https://farmersfriendllc.com/products/season-extension/caterpillar-tunnel