if it's from wm, it may be polyester ripstop rather than nylon if you don't know what you are looking at. order some free samples from www.owfinc.com
once you see the differences, you will always be able to tell the difference between 1.9, 1.1, sil, and coated nylons just by looking at them. the first time you see polyester ripstop, you will know it b/c it is just "different" than nylon. silkier, softer, less stiff/wrinkly.
quest and owf have great prices on fabric. no 1$/yd, but still good prices. if you buy 15 or 20 yds, you get a big discount too.