Writing Done Right
Audiobooks are the fastest growing sector of the publishing industry.
Average Cost: Starting at $500, but cost share is an option
FOSS Software Options: Audacity, Kid3

Audiobooks are the fastest growing sector of the publishing industry, but they are also one of the most expensive. The good news is that most distribution platforms including ACX (Amazon, Audible, iTunes) and Findaway Voices (which feeds your book to dozens of platforms) both have deals with narrators and producers to share your revenue rather than paying the fee up front. This will allow you to send your book to audio platforms and libraries without the upfront costs that might otherwise become a hurdle.

However, do a little math on the expected return of the book, the expected sales, and your budget. Because you are splitting your royalties with the narrator, it may be more worth your cost to pay for the production up front. While that could cost over $500, it also means you get to keep all of your royalties instead of sharing them. Run some numbers and make your determination.

If you are more industrious, and have a clear, strong voice, you can narrate your own book (of note, non-fiction books are best narrated by the author, fiction...not as much). Producing an audiobook requires a bit of technical skill and dedicated equipment. You will not narrate your audiobook on a cheap microphone, so you will want a good studio setup in a very quiet location with sound paneling. The best FOSS software to produce audiobooks is Audacity. Learn a bit about how to get your audio file specifications to work with your audio remastering software.