As of now, you can get The Half-Made World by Felix Gilman for only $2.99 (€2.49) from Amazon and Kobo. At Kobo, in fact, you can apply coupons (see, for instance, the right side of the excellent Books on the Knob) to get it even cheaper. The book is DRM-free so it can be converted easily for any ereader.
This is the product description:
The world is only half made. What exists has been carved out amidst a war between two rival factions: the Line, paving the world with industry and claiming its residents as slaves; and the Gun, a cult of terror and violence that cripples the population with fear. The only hope at stopping them has seemingly disappeared—the Red Republic that once battled the Gun and the Line, and almost won. Now they’re just a myth, a bedtime story parents tell their children, of hope.
To the west lies a vast, uncharted world, inhabited only by the legends of the immortal and powerful Hill People, who live at one with the earth and its elements. Liv Alverhyusen, a doctor of the new science of psychology, travels to the edge of the made world to a spiritually protected mental institution in order to study the minds of those broken by the Gun and the Line. In its rooms lies an old general of the Red Republic, a man whose shattered mind just may hold the secret to stopping the Gun and the Line. And either side will do anything to understand how.