If what you want is the recorded performance of someone reading a book, then yeah, librivox for legal audiobooks, and other commentors have other amswers that are on-topic. But DRM-free ebooks

text things, like epubs

can be read aloud by good ereader apps. I like Moon+ Reader Pro from Google Play, and Cool Reader from f-droid. For me, the emotionless robotic reading of TTS engines is more like a hands- and eyes-free way to enjoy the author's words as written; I find listening to someone performing an audio reading of the book a different experience.

Before ebook reader apps learned about TTS I used to take my txt ebooks, feed them through flite (Festival Lite), then convert the resulting audio to ogg vorbis and load them on an iRiver PMP to play during long drives.