I noticed that you are asking $4.95 for the Kindle edition at present........ with only one review. $4.95 is a problem. It is at the high end of the new author's scale and very high with no additional reviews attesting to the quality of the writing. In the kindle world there is no lack of free or .99 cent books available.....good ones. But even at 99 cents a reviewer may still grump at the time and money wasted.
I suggest that you call for reviews and be ready to send out a free copy to get them. I'd start with people like Cedar .....those who provide a service for ex and soon to be ex JW's on line.
Also send a copy to other on line book reviewing sites. And I'd encourage you to check out the reviews of post apocalyptic fiction on Amazon et al. A careful study will allow you to target 20 to 30 reviewers who are honest, write well and have all of their reviews available. That's right.....make sure you review the reviewers. This is important because there are a lot scams at the 5 and 4 star review levels.
The other option is to offer the book free (for a week or a month) to the very readership most likely to be interested in it.............like the folks on this site.
Or If that is not appropriate for you.......... then ask for 99 cents.
In my own experience down loading books on kindle......... the reviews/subject and writing skills are the three most important aspects for any book that I am interested in. And I have happily recommended a good read to anyone who may be interested as well as buying the next book in the series at full price.