john, the stamps themselves were run in large quantities. The 50 sen stamp was the postcard rate at the time. The 1 yen denomination is a bit more difficult to understand as I don't think it fit any real purpose alone. (Perhaps the two stamps together fit the international rate?) About 600 thousand sheets were run, so one can't say they are uncommon. I've seen them go for about 4 dollars on
ebay (sometimes more, sometimes even less.) As they are fragile, perhaps condition matters most. I did see one example that I think was cancelled and the seller was asking a premium price. I assume it was something like our cancelled to order and that it was a first day of issue.