1.50. A man kills his wife, then goes inside his house and kills himself. (DH original, from "Nightmare in Yellow," by Fredric Brown)

1.50 answer: It's the man's fiftieth birthday, and in celebration of this he plans to kill his wife, then take the money he's embezzled and move on to a new life in another state. His wife takes him out to dinner; afterward, on their front step, he kills her. He opens the door, dragging her body in with him, and all the lights suddenly turn on and a group of his friends shout "Surprise!" He kills himself. (Note that the whole first part, including the motive, isn't really necessary; it was just part of the original story.)