Here's a tip for those, like me, who love their Kindles and Audiobooks.
if you buy the Kindle version of a book, if an Audible audiobook version is available, you can often buy that as well at a heavily reduced price. This can often be way cheaper than just buying the audiobook.
This also works for discounted, even free, Kindle books. For example. I recently got the Kindle version of Prototype D for free, and that entitles me to get the Audible audiobook for only £2.99. The normal price for the audiobook alone is £16.97. Often, this will also allow you to use Whispersync, which synchronises your audiobook and eBook versions so you can switch between them with ease.
I've made some significant savings this way. It's often cheaper to buy the Kindle version just to get the discount on the audiobook than it is to just buy the audiobook. The two combined are often cheaper than the cost of my 1 credit per month subscription on Audible.