My wife has bought some stuff from these guys when our Ghana fabrics ran out.....
http://www.aknfabrics.com. Although, once you wrap it, you lose most of the design, so any psychedelic odds and ends from your local fabric store works. I even went to the recycling place and looked through their free clothes bin, found some old pyjamas and business shirts that looked pretty good once I wrapped them around.
Be imaginative, worst case scenario, find some old sheets at the Salvos and tye dye them!!!!