Deeper Into the Void is available at several book sellers. Amazon.com, Barnes & Noble, Indie Publishers, Alibris and more all carry this title.
Pricing changes, but the book is available in eBook format at Amazon.com. The suggested retail price for the paperback version is $15.95 and the eBook is currently priced at $3.95.
You can get a copy of the book directly from the publisher at http://www.createspace.com/3487039/. You can use the coupon code: 6XXEP88X to get the paperback for $10.95 from this site.
Goodreads.com has a great system to search for the best price for online booksellers.