My first comic was a reward for being a good boy at the dentist. My mom said I could have any one from the rack, and I picked TUROK SON OF STONE (Dell, #5) because, of course, it had dinosaurs.
My dad worked as a baggage loader at the railroad terminal and brought me home out of town newspapers like THE NEW YORK JOURNAL-AMERICAN, NEW YORK SUNDAY NEWS and even TORONTO STAR WEEKLY, because our hometown papers didn't carry Flash Gordon, Buck Rogers, Brick Bradford, The Phantom, Mandrake the Magician, Johnny Hazard or Smilin' Jack, all of which became favorites of mine. I'm currently buying the hardcover reprints of most of those strips (do wish somebody would reprint BRICK and JACK though!)
I remember looking for a new Kirby monster book in the drug store and saw something titled "The Fantastic Hour." It wasn't entirely unheard of to issue a one shot comic with a book length story, especially when movie adaptations were common, so I didn't realize until I got it home that it was the first of a new superhero series called, you guessed it, THE FANTASTIC FOUR.
A couple years later I told my cousin about an advertisement for two new Marvel comics. One was called THE AVENGERS and the cover showed a JLA-like teamup of Thor, Iron Man, The Hulk, Ant-Man and The Wasp; the other showed only the logo, X-MEN. My cousin accused me of making it all up because Marvel would never copy DC like that.
When our town's first comics shops opened, I walked in when the owner was out and had left his wife in charge. I saw a copy of ALL-STAR COMICS #21 lying on the counter and asked her how much. She said, "Oh, it's a 10cent book ... I'm supposed to ask for more than cover price. Is 25cents okay?" I slammed a quarter down, took the book and never went back for fear the owner would demand it back. It must have been worth about $25 at that time.
Not comics, but another memorable experience was finding a bookstore whose basement was filled with tables with stacks of old comics and pulps. All the really good ones were taken, but I did find a run of STARTLING STORIES with Captain Future short stories by Edmond Hamilton. Hamilton and his wife Leigh Brackett became my favorite SF writers.