I've bought a few screens (5 or 6) before I started making my own and despite far longer journeys US/UK all arrive unbroken.
David, I looked at your packaging and thought they'd break. The glass needs to be between foam or something then the more rigid packaging. I actually have a box that contained a 10x8 screen and you could throw it around and the glass would be difficult to break because the shock is absorbed.
You need board / foam/ glass / foam / board then a Jiffy bag, the foam for my 10x8 is about half an inch thick.