Heritage Auction Galleries feature very interesting animation-related items once in a while.
http://www.ha.com/
I came across a recent auction featuring a very rare 1947 Disney Cheerios Premium. (a mini-comic inserted in a package of Quaker Oats I wager...)
"Donald Duck's Atom Bomb" features appearances of Huey, Dewey and Louie with art by Carl Barks and was banned from ever being reprinted for obvious reasons.
This tiny booklet has an Overstreet value of $538 according to Heritage's records. Does anyone have any more information about this rare story?