If you don't want to hire anyone to do it for you, the basic technology to create an audio book is fairly simple. You just need a $40 microphone and some software. It's pretty easy.
The actual recording his harder. I recorded a travel magazine for a local lower power FM station and it's harder than it looks. You don't hear until it's played back all the little noises you make that distract from the experience of listening.
To do it right, you need a good reader and a sound editor. At the minimum get a good sound editor. It'll go along way towards making your audio book great.
If you want to know the type of microphone and the software I used to record my parts were, let me know.