The ones for the R57s will work also. I sold one to a friend and it worked fine in her 1st Gen. That might make it easier to find since the 1st and 2nd Gens both work in the 1st Gen.
I checked on ebay the other day. Several R57 deflectors were available at a wide range of prices. There was on claiming to be for the R52 that was priced a little over $400. That's more than they sold for new, I'd give that one a wide berth.