Does anyone know what the deal is with a (Mighty) Avengers (Vol. 1, 1963) #91 variant that doesn't have the 15 cent price on the cover? You can see an example of this book at comicbookdb.com Instead of the price, there is the following "1/-" I have stumbled across one of these in my collection and I have no idea what it means. Suppositions range from some sort of foreign country variant to a later reprinting. Any help would be appreciated. This issue is part of the Kree-Skrull War Saga.