Many years ago I came across a large roll of quite thick white fabric at a cheap price and painted one side black and the other approx 18% grey and have got a lot of use from it. I used cheap interior wall paint and applied a couple of coats with a roller. If it is typically out of focus in the shot then the occasional marks, scrapes and dirt it picks up with rolling and unrolling and people walking over it don't matter too much.
My avatar was shot in front of the black side.