I had this made up as a rain cover at PARKER ENTERPRISES, Harrison, AR. It is made from heavy Codura Nylon and the best quality made in the USA. They should have the pattern for mine, which is designed to cover my tank bag as well. These folks are very flexible when it comes to working with you on your design and they can also do monogramming.
http://www.parkerems.com/aboutus.htm JD
P.S. This is Bev, JD's other half. I couldn't help but notice that Man of Blues has a shop just as organized as JD's.