Amazon is now reporting that "Unfit for Command" usually ships in 5 - 7 weeks. I believe that this means that it is not in stock.
http://www.bestwebbuys.com/Unfit_for_Command-ISBN_0895260174.html?isrc=b-search
This web page lists various sellers/prices/estimated ship dates. Note that Barnes and Noble list it as "n/a".
Not only is booksamillion listed, but there are other sellers such as Powells.