A judo costume is among a selection of Palitoy Action Man accessories to sell at Vectis Auctions in Thornberry, UK later on this year.
Palitoy released the first Action Man figurines during the 1960s
Valued at up to £20,000 ($30,766), the lot is so rare that its existence remained unknown until recently.
John Cathrall of Vectis explained: "It belongs to a Palitoy rep from Essex who has had them in storage since the firm went bust in the 1980s.
"The judo set is the Action Man Holy Grail, supposedly none existed, but I knew they did exist. Out of the box it would sell for about £1,000 but in the box like this one it could be up to £10,000 or even £20,000.
"You can't really put a price on the judo set, it could just keep on going up and up."