I did a simple studio setup with 3 borrowed 580ex a couple of months back, went to get cloth from arab street for plain white cloth, got a few cans of spray paint, 2 stands, 3 bamboo poles and 1 roll of nylon string... walla, the effect turned out to be pretty good.
Just spread the cloth in the sun and spray your colour on, wait for it to dry then crumple it a little. and your makeshift backdrop is ready for use!
Ps: u need abit of skill when u apply the spray paint...