Actually, you can buy a pad sleeve like this from DownWorks in Santa Cruz, CA. They make different sized sleeves, with different sized zippers, to fit various pads and bags.
They also make pretty darn light custom quilts, too. I haven't weighed them but I'm sure they compare favorably to any other quilts of similar size, and the quality is outstanding.
I don't know if they take phone orders, but they don't have a webpage that I know of. It's just a guy and his wife in a ~900sf shop full of respected brands (WM, Montbell, etc) and some of his own creations...his sewing machine is right there in the front room and he's usually toiling away if he's not helping a customer.
222 River St
Santa Cruz, CA 95060