Last year we bought an expensive heavy duty tarp from our local hardware store to cover our hay, it lasted all of 6 months. Thanks to some helpful advice from the folks at http://www.homesteadingtoday.com/ we called a local billboard company to see if they had any signs they were taking down. The company said yes and below is what we got. What you can't see is that the underside is advertising a housing development. The signs are heavy duty reinforced vinyl and so far so good. And the best part is that they were free!