My Amazon titles use Whispersync to seemlessly sync with the audiobooks. This means that if you own the ebook, you can get the audio for really cheap, and then automatically switch bewteen reading the book and listening to it.
If you listen to a lot of audiobooks, I recommend becoming an Audible member. Audible gives you one free audiobook per month, and dramatically discounts any more titles that you buy. It's a great deal if you're a medium-to-frequent audiobook listener. You can start by signing up here and getting any of my audiobooks for free.