This Time-Life: Mysteries of the Unknown TV commercial from 1989 is a true blast from the past. The full 33-book set (subscribers got one book a month for $12.99 plus shipping and handling) goes for $475 on ebay. Incomplete sets sell for a lot less, though!
I would love to own a set! Here are the titles:
* Alien Encounters * Ancient Wisdom and Secret Sects * Cosmic Connections * Cosmic Duality * Dreams and Dreaming * Earth Energies * Eastern Mysteries * Hauntings * Magical Arts * Master Index and Illustrated Symbols * Mind Over Matter * Mysterious Creatures * Mysterious Lands and Peoples * Mystic Places * Mystic Quests * Phantom Encounters * Powers of Healing * Psychic Powers * Psychic Voyages * Search for Immortality * Search for the Soul * Secrets of Alchemists * Spirit Summonings * The Mind and Beyond * The Mysterious World * The Mystical Year * The Psychics * The UFO Phenomenon * Time and Space * Transformations * Utopian Visions * Visions and Prophecies * Witches and Witchcraft