There was a recent episode of Pawn Stars on The History Channel where a guy brought a map of Iwo left to him by his father. They were older than the ones you have, dated 1944. I can't find the episode online anywhere yet but did find this synopsis of the show.
"The first guy brought in maps and battle plans for the battle of Iwo Jima. The maps and plans were from the gentleman's father, who was a coxswain in a landing boat. The guys went to Mark, from the Clark County Museum, which is located in Henderson, on Boulder Highway. Rick's first offer was $2000. The guy countered at $2700 and it went for $2300. He wanted the money for his daughter's wedding."
I think you did well to hang on to them and not sell them for a grand.