Have you thought of selling advertising to be printed on the commercial canopy you take to flea markets and farmers markets? The paid advertising could more than pay for the printing as well as your canopy and maybe give you an additional income. It also benefits the advertiser with a wide exposure to a varied crowd.
After your commercial canopy is printed you could continue to sell advertising by using free standing banners. They are versatile, attractive and those passing by your booth will surely see them. Be creative and you'll be making more money than you expected this season.