I'm an experience sewer and I have made one simple kite using standard ripstop I picked up at a local fabric store. However, I'd like to pick up my game and make a dual line sport kite. But almost all the patterns call for Icarex fabric, which appears unavailable from domestic sources (though there do seem to be rather expensive European sources). So, I started looking for substitutes. Posts from a year ago indicate that folks were using Airx 600n as a good substitute--at the time, Kitebuilder was selling it (they even have an info page on the fabric) but they don't appear to have any yardage for sale anymore. I see I can buy it in large quantities (but I really only want a few yards).
So, I searched online for .5 oz ripstop. I have found two options, but I don't know if they are any good:
Nylon, not polyester: http://search.sailrite.com/?freeText=.5oz%20ripstop
Mystery fabric, but FAQ indicates it is .5 ripstop: http://wildrc.com/htmlpages/orderairframemat.html
Also, I notice that sailcloth is measured for weight over a shorter yard than a sewing yard, which leaves me wondering if my stash of ultralight silicon embedded nylon ripstop (which I think is rated .9 oz/normal 36" yard) is ok. It is definitely softer and more drapy than the materials in the kites I've bought.
OK, I hope someone sends me a source (or validates what I've found). I wanna stop shopping and start sewing!