Well, technically, such a thing couldn't be sold. Contractually Wacky sketch artist's can't sell an unused artist return card blank and all return cards need to be approved by Topps before they are sold. In the past, sketch artists could hold onto blank return cards and take their time doing them so it's possible artists still have some blanks. Presently Topps is asking artists to complete return cards with their set cards so from now on blanks won't exist once the set is completed.