For packing kites for traveling i find a waterproof backpack liner from a outdoor store are good.
There super light very strong and take up little room, they dont have a draw string but just a simple roll and clip that forms a handle that is air tight so you can compress the kites as little or as much as you want.http://compare.ebay.com.au/like/1509601
Excellent suggestion! I'll look into this more, thanks! I'd be happy to give up its watertightness for a shoulder strap.