I just wanted to provide an update and end this thread. We are not going to get an mp3 player. I just found out today from her that she has a Kindle and has downloaded books there and it has text to speech and actual audio books.
I played with it and indeed it works very nice. Anyhow I got it connected to the car stereo and we could hear the books. So no more to need to look for or buy an MP3 player. Sorry people for the false alarm but I did not know anything. Still I have saved all links and thanks all for the advice.