Thanks for your interest in my forthcoming book. I am still busy working on the index, which I hope to finish by October (it is a tedious and time-consuming task). Sometime next summer, I will be in contact with prospective publishers. Until then, I can't say what the cost of a two-volume set will be or exactly when it will be available for you to order. I will be happy to send you a pre-publication notice when the time comes.