You don't need a reading device to be able to see what your books will look like on a reader.
Amazon have a free download called the "Kindle Previewer" which will give you an accurate representation of what your book will look like on a Kindle device, as well as on the various Kindle apps for PC, iPad, iPhone, Android, etc.
For ePub, download the free "Adobe Digital Editions" software from Adobe's web site. ADE is the basis of the ePub firmware on most reading devices, and will give you a very good idea of how your ePub book will appear on an ePub device.
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