I really like DIY Gear supply, and seem to be ordering from them regularly.
Dutchware is great. He used to have a remnants area, but either I can't find it these days or he has done away with it. He is heavy into hammocks, but sells fabric and supplies that are useful for all kinds of things.
I have done business with Quest and they are great. They may be in Florida, but things get to Arizona very fast from them.
Ripstop by the Roll often has great prices and $7.95 flat rate shipping.
I have also done business with OWF (they had some really heavy nylon cordura I used to rebuild my cots). Their website is pretty bad, and sometimes doesn't work at all. I hear that if you order 20 or more yards from OWF, they will give you wholesale pricing (about a dollar off per yard). And I am told the 20 yards can be mixed of the same type, where for example the "type" is ripstop.
Most fabric is 60 inches wide and is sold by the yard. Typical prices for nylon ripstop is $6 per yard, so if you find seconds or remnants for $3 per yard, it is a great deal.
I recently visited a nasty "fabric remnant store" in town. They were selling random pieces of non-technical fabrics for $5.00 per yard. They were calling this a "bargain". Based on that data point, getting a yard of ripstop for $6 is a great deal.
Tom's hiking pages / [email protected]