Audible is having a "First-In-A-Series Sale". The sale books can be seen at https://www.audible.com/ep/s/first-series-sale. Their e-mail says hundreds of books are on sale.
One that caught my eye was "Wool Omnibus Edition (Wool 1 – 5)" for $6.95. https://www.audible.com/pd/Wool-O…B00904FYUI
There are tons more good first-in-series books on sale though.