The first novel in the Theo Waitley arc of the Liaden Universe(r),
Fledgling, is available for $1.99 as part of the Audible "Treat Yourself" sale. This book is an excellent entry point into the Liaden Universe if you haven't read any of these wonderful books before, and is well read by Eileen Stevens.
Fledgling is a YA coming of age story, but don't let that stop you - this is very much a series that adults can enjoy equally. The Liaden stories are character driven, not technology driven, and are the sort of books that can be read and re-read many times, IMO. Even if you've read this book before, I recommend getting the Audible book at this price.
Listening to a book is a very different experience in many ways, and I predict you'll get new things out of the audio book.