I think Nintendo games CIB might be a little more rare than you think. I have very few and the few I do have aren’t in very good condition. The majority of people didn’t hang onto them, and even for those that may have tried, chances are something may have happened to them through the years. I tried to hang onto my SNES and N64 boxes, but I think I either decided they were just taking up room, or they were being stored at my parent’s house and they threw them out when they moved.
What you’ve got there is pretty impressive IMO.