If anyone's interested, I did end up getting TextAloud and two of the voices from Acapela Telecom (you have to get the 22k voices, they're just fantastic) and it sounds really, really good. Not mechanical at all, with good intonation.
I got a Heather voice and a Lucy (UK accent) voice.
I'm uploading an mp3 at the moment and it'll be up soon for anyone interested in checking out the voice/listening to an article about a study on meditators (it was posted in Health forum a little while ago).
Edit: The link is here:
TextAloud-Meditation Article.mp3
Enjoy!