This list is not complete by any means, but it represents all that I have found. A sad note here is that it seems that SFBC has decided not to publish anything from Piers Anthony for quite some time now. I noticed that SFBC seems to favor only a select group of authors and Piers, as well as many others that used to be published are no longer offered. I am not aware of any offerings for Piers books in a few years. I guess this should drive up the price of the books, but it really has not seemed to have made any difference.
Most volumes are readily available in the used book market or at auctions.
After The Magic of Xanth, SFBC started publishing individual hardbound editions of Xanth novels since they were being published as only paperback in the mass market. There is no Book Club Edition date given. No other books were published after Man from Mundania. E-Mail Me Books, photos, images, and other content are copyrighted by Piers Anthony Jacob and his various publishers. No copyright infringement is implied.