I've spent a great deal of my life (and income...) tracking down many hard to find comic books.
I've amassed quite a collection over the years, to be precise about 15,000 comics. I started back in college, collecting the entire series of Star Wars from Marvel and some Spiderman books, many which I had as a kid but lost during a move. I didn't stop once I was finished, I branched out into many different current and out of print books and still pick up an occasional "treasure" from time to time.

My oldest book is a Four Color Comics #5, featuring the first appearance of Raggedy Ann/Andy published in 1942! The WW2 era books are very rare to come by as paper recycling was a big thing during the American War Efforts. Probably my most valueable is Fantastic Four #48 (1st Silver Surfer) in VF+ condition.

Amazing Spider Man #129

February 1974
Written by Gerry Conway and illustrated by Ross Andru (also recently deceased and missed). This issue featured the first appearance of "the Punisher," a controversial character that is willing to take the lives of his enemies, something that had never been illustrated in a comic until then.

Unlike conventional heroes who would pummel their arch-nemesis into submission (and would sooner or later escape captivity to further torment the hero), when the Punisher kicked someone's but, it STAYED kicked!