The last time I got some it was grey. First I weighed mine, then I made a tarp of it and tested for waterproofness. Mine weighed in at about 1.2-1.3 oz per sq yrd. So, you might have found it. How wide is the fabric? Mine turned out to be 48" instead of the standard 60" wide.
A couple of years ago my wife was shopping for some fabric at an out of town Walmart, and I found a bolt of 1.1oz ripstop. It was marked $1.99, and whether the clerk was incompetent or what, they sold me the WHOLE bolt for $1.99. I think the clerk may just have been too lazy to measure how many yards were there. It turned out to be about 10yards of material, if not a touch more... I've just started making some stuff sacks and now just finished an 8x10 flat tarp. So far with the grosgrain guy-outs sews on, it's at about 11oz. I plan to try siliconize it myself, following some of the many instructions found online.