Tim Ferris’ team compiled three volumes of letters and information about the Stoic, Seneca and Published it for free.
Free Seneca PDF Books
You can easily read these on Kindle, and Tim put instructions of how to send the PDF to kindle at the link above. If you don’t have a kindle yet, please get one using this link. A kindle is an excellent device that will allow you to carry hundreds of books with you at a time.
The books of Tao of Seneca are free, but the audiobooks are not. However:
You can get an audiobook for free using one of the links below
Tao Of Seneca Audible
Tao Of Seneca Audio | Volume 1