Dr Kashif is here and avoiding formalities, let me tell you that I have sound experience regarding this. Recently,I am working on a task related to the short biographies (audio & video files) of specific personalities to publish in one book.
My offer for 30 to 40 minutes recording is 25 dollar to 30 dollar.
For 60 to 90 minute recording, my offer is 40 to 60 dollar. Roughly, I have mentioned payment but we can decide later based on fair dealings.
Because of having experience of writing books, I can be supportive in many ways like editing and proof reading and a lot more
In the world of proverbs, it can be said,'' Killing MANY(not 2) Birds with one stone
waiting for your response.........