I recently started reading a pBook - Area 51. It's part 1 of a series. However none of the bookstores in the Netherlands have this book in stock. So I decided to do quick search.
The publisher is kind to provide a full overview
pBook Titles: 9
Audio-book versions: 6
eBook versions: 2 (Book 8 and Book 9) Price identical to the pBook version
I found PDF-versions in dark and obscure places on the internet for Book 1, Book 2, Book 3, Book 4, Book 5, Book 6, Book 8.
Publishers just don't take me serious as consumer providing an (some) audio versions but not an e-version for all books from a series.
(for thos who wonder - I just ordered all pBook versions so the author can buy a sandwich - and I'll use the "illigal" versions on my e-book reader)
I totally agree with the initial poster: publishers get your act together and provide cheaper e-book versions for all ALL (e-) books (even those out of print) so I can purchase a legal version, and you might prevent the mess that the music and video industry is currently in.