I ordered the first three volumes of Railroads of Arizona from Mike Dreiling (a member of the On30group site at Yahoo!). They came today and they were better than advertised and packaged very nicely. If you need an out of print book, check with Mike on the On30group site. Highly recommended.
Now I have a lot to read before I go much further with the module. I am not trying to do historical modeling but I do want to be true to the area and era I am modeling as far as building techniques, major landforms, and the general political/cultural climate.