I was born in 1970, and as a kid in the 70's living around the Detroit area, I used to watch lots of Japanese shows on TV at the time. There was the classic Godzilla movies with guys in monster suits stomping on model towns and fighting with each other, there was Ultraman, and also Johnny Sokko and His Flying Robot. All my friends and I used to watch these. We're all in our late 40's to mid 50's now. I assumed all kids from my era saw these shows, but maybe these shows were more area specific and not everyone saw these all over the U.S. and world. I also seem to remember these shows kinda disappearing from TV somewhere between '76 and '80, so I can understand younger folks not being familiar with these franchises.
I do dig the Ultraman theme, as it brings back some warm and fuzzy nostalgia. If I was in the market for one of these pins I'd try to grab the Ultraman from nostalgia alone. I also like the Halloween too though, although that brings back a different kind of nostalgia which is not quite as warm an fuzzy, but a little more psychotic and murderous, LOL.