Digital copies (and bundles) of all my books can be purchased at my online store: http://shanewsmith.com/store
If you’d rather go through a reputable retailer (and who could blame you), here are your best options.
The Lesser Evil
The Lesser Evil is currently out of print. The new edition is coming in October 2017.
Peaceful Tomorrows is currently out of print. The new edition is coming in October 2017.
All The King’s Men
Undad Volume Two
No purchase needed. Read it here for free.