If you know your comics history, then Action Comics #1 from June 1938 means one thing to you, SUPERMAN.  This is the comic where the last son of Krypton made his first appearance in the world, and this particular copy has a 9 out of 10 CGC rating, meaning it is as close to mint condition as almost any copy around today.

The previous highest for sale of an action comics #1 was a cool $1 million back in 2010, but this particular copy sold over the weekend brought in a new record of $3.2 million.  So go raid those bargain bins!