There is a great location for cheap building supplies called The RE-Store, which is sort of like Goodwill or Salvation Army for Habitat for Humanity. I've picked up lots of things like hinges, windows, doors, linoleum, drawers for nesting boxes ($.50/each) there. Lumber, interior paneling, plywood are sometimes available but get grabbed up quickly. I'm almost done with my 4'X8' coop (fully insulated) with a run underneath plus and additional 6'X9' run and have spent somewhere between $250 and $300, mostly spent on 2"X4"s and chicken wire. Lots of the materials are left over or reused from various building and remodeling projects, You might look on-line or in the yellow pages for salvage or reclaimed building supplies as well.