There are a couple first-time-free paleo books:

Everything You Need To Know About The Paleo Diet by Diane Wilson
http://www.amazon.com/dp/B00CNIMLSG

Paleo for Fighters by James Gregory
http://www.amazon.com/dp/B00CJIAEQG

The author here stuck paleo in as a tag. This is for people that like 
mystery self help books. Until you buy the book you are not told what 
the author is recommending.

Emergency Weight Loss - How to Lose a Dramatic Amount of Weight in 4 
Weeks by Billy Timmins
http://www.amazon.com/dp/B00CNAFW8K

It is the same author that had "Lose Weight Slowly!" free a few days 
ago. He likes to play both sides of the fence.

There are also a bunch of others that were also free in the past. See:
http://www.amazon.com/s/rh=n:283155,k:paleo,p_n_feature_browse-bin:618073011&sort=price