You might want to try the ebooks written by Richard Tuttle and available at Fictionwise. the books are all DRM- free multiformat and audio books (I've never tried one so I don't know how well read they are) are available. They are inexpensive and excellent. There are 4 series, all linked together (i.e., same characters but different time periods). I reviewed the Sword of Heavens series
here. The series titles are:
The Demonstone Chronicles; Forgotten Legacy; Targa Trilogy; Sword of Heavens. You can do a search on Mobile Read for Richard Tuttle to find other comments about his books.