Call Dave at Winsol. They make a product called Awning Armor. As far as streaks go, that is dirt. You have to regularly clean and protect awnings every three months not twice a year. Doing it once a year will not be frequent enough. As far as pricing goes, try to figure out how much they would have to pay to have the fabric replaced due to premature oxidation and sell them on your service as an extension of the normal life expectancy of the fabric.