I have seen the jackets. They are made of tyvek. I think there is a source making the tyvek sectionals for carriers that require stronger sectionals. I don't know where to find the material, but here is a website selling the jackets, shower curtains, and aprons. They may be able to point you toward the source.
Those T-shirt transfer thingies give mixed results. They have improved in the last couple of years, but you still get a fair amount of color fading with only a wash or two. Now, presumably you'd not be washing a quilt often, but I would suspect that if you spilled something on it there's a good chance you'd have a mess on your hands.
