Amanda has many more amazing resources over on her website 

http://amandafrancey.blogspot.com.au/p/kids.html

The 'Dark Star' audio book is just under an hour worth of listening time and is available for .99c on Teachers Pay Teachers  as well as Audible for $4.56. Unfortunately I am not able to set the audible price any lower, but the direct download from TpT is a great option for schools and educators.

From time to time it'll pop up under the middle grade tab for free.