I think Gary at BAMW can source them. Or try Seibenrock - I seem to recollect that they sell them.
Or get Roger at Ard Cases to make you up a metal one, like mine!
my panniers ( on the GS PD that is) are from Andystrapz in Australia. Had them a few years now, and they are great- very tough, loads of room, very light ,and almost waterproof. I use his waterproof inner bags to be on the safe side. Andystrapz do some really good stuff, panniers, straps, rear bags etc - all tested by Andy, and made to endure the rigours of the Outback. Good for Tesco's too of course.
Thanks guys...yep it was the PD I was talking about...mine is just about ready to go back on the road. Thanks for the advice...just what I am looking for. Liking the Ardcase as well!