(Not sure if someone gave this a mention a while back, or at least mentioned red white curtains.)
I was near, so I popped over to Ikea yesterday, seemed like a potentially uncrowded day, and it was. Someone had told me they had striped cottons.
They have several ranges, ELISABET, SOFIA, SONJA. a mixture of subtle and very bright stripes.
It is 100% cotton and whilst nowhere near the thickness of canvas, could possibly be used on an indoor booth.
http://www.ikea.com/gb/en/catalog/products/10120653
http://www.ikea.com/gb/en/catalog/products/80116718
http://www.ikea.com/gb/en/catalog/products/10117052