In all honesty, your question was a little confusing. You said childhood- '80's and '90's, I mean there were actually 2 Iron Man #1's printed in the 1990's (Heroes Reborn, Heroes Return, and probably some mini series thrown in there). So, cool if you have a nice copy of a 1968, but MINT is a tough word to throw around on a comic book, unless 2 parties *buyer and seller, or an outside grading service *like CGC can agree on it. If you plan on selling, it may be best to go the CGC route to get max value on ebay or auction for your higher dollar books.
Welcome to the boards, hope you can find answers to your questions.