The most expensive comic book ever sold, $3.2M.

Produced in 1938, the comic marked the first appearance of Superman and is considered the genesis of the superhero genre of comics (although there is some debate about that)

Why so expensive?

The reason it was in such impeccable condition was that the while the first owner bought it for 10 cents from the newsstand in 1938 like 200,000 other people did, unlike most everyone else he lived at fairly high altitude in the Blue Ridge Mountains of West Virginia and when he finished reading it, he put the comic in a cedar chest where it remained virtually untouched for four decades. The cool, dark, dry environment of the cedar chest froze time for this comic.