Dang Dave you do nice work. The most creative I've gotten with a bag is a barber pole/candy cane type thing.
8 foot long bags? just how big are these kites?
If nobody steps up here ... bags are easy, any seamstress could make them up if your just looking for a drawstring or foldover top, Check your yellow pages for sewing or alterations, alternately leave a message at your local quilters shop. Ask whoever to finish those inside seams with some double fold bias tape if they don't have a hot cutter, it'll cost a bit more but you will be thankful you had it done.
eBay has plenty of deals on fabrics, if you want something durable search for "Cordura, Fabric" or "Cordura, Nylon" the 1000D is pack weight, 500D is half that weight I think. Running $6-12 a yard with buy it now, 60 inches wide, you won't find it at a yardage store anywhere near that price. That pink camo is the bees knees