Nature has an Insight article written by Chris Llewellyn Smith
titled "How the LHC came to be." Although the ILC is mentioned
just briefly, the subtitle, "Approval of a project the size of
the Large Hadron Collider is an exercise in politics and high finance",
could just as easily be applied to the ILC, so may be of interest.
You can read the article online at:
If you do not have a subscription you might try contacting
your university or lab library.