Re: Need some help choosing some more books?
O'Sensei only "wrote" two books, both well before WW2, and much of his philosophies and musings changed after that time.. "Budo" and "Budo Renshu" do have diligently-prepared English translations, but those are still interpretive. Much of what is written about his philosophies are in books authored by his progeny, Kisshomaru Ueshiba Doshu, and the present Doshu, Moriteru Ueshiba. Look for them. There is an English translation of Kisshomaru Doshu's biographical "A Life in Aikido" due out shortly (Amazon is taking pre-orders).
Also, anything by John Stevens will be thought-provoking, although the accuracy of his interpretation has been the subject of some discussion. But that could probably be said about anybody's writing on the subject. You may find "Enlightenment Through Aikido" by Sunadomari Sensei to be interesting. There is good material in many of Saotome Sensei's writings also.
Before you tie a ton of money up, try to get an up-front look at all this stuff at your library or bookstore.