Audio Creation Exchange (ACX) is the audio book arm of Amazon. They seem to be “the only kid on the block.” Everyone uses them because they make it so darn easy. When you are the writer, formatter, publisher and marketer, it is good to take it easy when you can.
With this site, you set up an account and post a few manuscript pages you think would give a good example of the voice you would like to hear read your work. You can request male or female, kind of accent, character voices, and so forth.
ACX has a stable of narrators. If one or more have interest in your piece, they do a recording of it and send it to you. You listen and choose. The lovely thing about this is that once you make your decision and have a 4×4 cover design made, you are out of the picture. The narrator uploads his or her work and posts it for you.