Ransom by Edward Wellen (F&SF, July 1977) has a good hook:
First the finger, then the ear, then the nose.
But before them, the tape. The tape came in the mail that caught up with the traveling mansion of Peter Kifeson. The tape showed a trembling Junior Kifeson in a limbo shot—no background visible, no furnishings. A two-shot, with the light on Junior and the masked man holding him at blaserpoint, and darkness all around them. You had the sense, however, that this scene took place in a small room.
Old Peter Kifeson watched, listened, and chuckled. Twenty-five million credits, indeed. But at least and at last Junior was thinking big, showing drive. About time. After all, Junior must be all of sixty. p. 92
When Kifeson later receives a finger in the post he publicises the fact but refuses to pay the ransom (he still thinks his son is behind the extortion attempt). When an ear and then a nose arrive, Kifeson changes his mind about his son’s involvement but continues to hold out.
The police (spoiler) eventually find the blackmailer and a dead Junior. Kifeson decides to clone his son, and the last couple of paragraphs make an unclear point about parenthood and filial love.
* (Mediocre). 1,500 words.