Hi Steve ! For you and others who may be interested in owning 'The Story Of Civilization' I will suggest simply looking in your telephone directory for the used bookstores in your area and making calls. You may find that this set is not as hard to find as you may think.
I purchased an almost mint condition set complete with perfect jackets from a local bookstore for $100 - 11th volume SIGNED BY WILL DURANT. I also bought another set at an annual bookfair in my city last April for $40. Though not in "mint condition" the second set was still in very good shape (minus jackets). They had about 4 sets at the fair as I recall all going for about the same price and all in pretty good shape. I have also managed to find two copies of 'The Lessons Of History' in "like new" condition in my town. One cost me $6 and another, at the fair, unbelievably, $1. I keep one copy with each set. At another local bookstore I found the 1941 edition of 'The Mansions Of Philosophy' ... I am looking at it now as I type this ... and on the inner leaf, still lightly penciled, is the price I paid of $7.50.
If you are a "reader" and not a "collector" as I am I would suggest just going for the basic set and saving the additional money required for the leather-bound series for other books by Mr. Durant. A less expensive collection of these volumes, even if pieced together singly, is still a great addition to any personal library.
I take volumes of the "bookfair set" to work with me to read before work and at lunch time armed with the confidence that if anything happens to it I still have the better copy back at home. The copies of the "mint condition" set never leave my house. I suppose what I am trying to say is that if you want these books for the practical purpose of reading them you shouldn't have to be afraid of handling them and accidentally damaging or losing them. Will wrote them to be read.