Audible has a sale for 2 audible books for 1 credit through March 29th.
Get 2 Books for 1 Credit [audible.com]
Only credit purchases are eligible for this sale. To redeem this offer, follow the link provided and add two audiobooks to the cart from the selection provided. When you check out, you will be able to purchase both audiobooks for one credit - either by using a credit you have, or by purchasing one at the time of check out. Offer is for Audible members only. Offer is not transferable and cannot be combined with any other offer. Sale ends March 29, 2017 at 11:59 PM PT (US).