It doesn’t look as if the published is planning an e-version anytime soon. The best place to go for the paperback is The Book Depository [http://www.bookdepository.com/Libertarian-Anarchy-Gerard-Casey/9781441144676] which usually offers a discount and ships anywhere in the world free.
I hope you can get your hands on a copy soon and that when you do that you find the effort worthwhile!