I build a twelve foot wide backdrop from some PVC pipe and white, 108" wide muslin cloth. The cloth is suspend from the wood ceiling by the PVC pipe, string, and screw-eyes. The sides of the backdrop are pinned to the walls with clamps to stretch out wrinkles.
All the materials for this came in just around $50, a real deal. Nate and I are planning a snowy indoor shoot this weekend, so we will put this set-up to the test!