I've been keeping an "eye" on this prefix. Recently saw on e-bay a G/R note in the 9 million range. This means that I have now seen G/R non-test notes from the < 1 million range, the 1 million range, the 2 million range, the 3 million range, the 4 million range, the 6 million range, the 7 million range, the 8 million range, the 9 million range, and in the 5 million range I have seen non-test notes below, above and between the test note ranges. This would suggest to me that the full prefix was released.
With the recent discovery of E/R test notes, and G/R test notes not being terribly old either, some collectors believe that there are still more test note ranges to be discovered. Therefore, these people are buying up the cheaper non-test notes in hopes that one day they might be declared test notes. This increased demand and buying activity is thus driving the price upwards. There is no evidence at this time to suggest that there are any more test note ranges to be found in the G/R prefix, or any adjacent prefixes, and indeed, the best information available at present indicates that all test note ranges have been found.