Bottleneck on Amazon
Initially the book was only available as an eBook in Amazon Kindle format. This allowed me to make it available at a very low cost. If you have bought anything on Amazon, you will already have an Amazon account, so you can buy the book with just a few clicks.
You don’t need a Kindle to read the Amazon Kindle version
The eBook is now available for the iPad, Nook, Kobo etc.
Or from Smashwords: