Where can I find super cheap fabric or tablecloths?

Setting up my clroom, and want to make groups of desks for students to sit at. They will be at a different area each day - with 43 students, I can't speak to them individually and wanted to set up stations - so I could say: John, Molly, Jess, and Tim to the Tiki Hut; Matt, Jim, Susie, and Jen to the Sports Complex. I would like to have tablecloths or make tablecloths to cover the desks, I have no budget and need to buy everything myself.....Where can I find cheap yet durable (students using them everyday) online. I live in a rural area and there is no retail stores available. Thanks in advance for your help.