You will definitely want a professional voice talent who has much experience to perform long form narration for you if you'd like the best results. Ultimately, the book will not sell if you do not have a narrator who is flawless in their execution of their performance and has the knowledge of many other books under their belts already. I have personally recorded over 150 audio books for several authors some for ACX, but most for large publishing companies who post their project directly to Amazon.
The bid for my services is inclusive my voice services for up to 11, 000 words, professional studio recording, clean up edit, edit to chapter and conversion of each to chapter to audio file of choice for delivery via the internet. Typically, for ACX or really any audio book that either streams or is downloaded is MP3 format.
My turn around is 4 business days (Monday through Friday) from receipt of the award and funding of your escrow.