Finding pagan and Wiccan pdf's and ebooks are hard enough to find for free considering the copyright infringement issues that it proposes. And it is even more difficult to find the specific titles you are looking for, especially the more popular and mainstream a title is. However, the bulk of free pdf's and ebooks that are available are usually out of print and outdated materials usually of obscure or historical nature than detailed information about Pagan and Wiccan spirituality.
I have only found one free audio book on paganism and Wicca, and that was a major disappointment as it was by Alexander Gardner, of whom I am not very fond of. Despite this seeming a small comfort, if you have an Amazon Kindle, depending on the generation and model any ebook or pdf can be turned into an audio book per say using the experimental feature called text to speech in which the device will read your ebook or pdf to you in a male or female automated voice. Amazon does have some free ebooks on the subject but again they are old and outdated titles, that are very difficult to read with ease.
But if your an avid reader like myself you can try extensively searching for free audiobooks most likely on Open Library,Project Gutenberg, or some of the other public domain ebook and archive sites. If I find anymore or other sources I will gladly pass them along.