Action Comics #405 Artwork

While chatting with a friend who just scored a Thomas Kinkade painting, it got me to do some digging on the original Curt Swan/Murphy Anderson artwork for Action Comics #405 (October 1971) that I own. It was for the story, "Superman, Bodyguard or Assassin?"

Here's the page:

And here's the cover to the comic it's from (by Neal Adams):

I must've bought the art page about 10-12 years ago. I paid $100 for it. Checking around, it appears that comparable original art from Swan and Anderson during that period now fetches around $500. See this.