The link is for Kindle books that can have Audible narration added for under 3.99. Some titles inaccurately have a higher price for the narration.
I performed these steps with the book Moving Mountains by John Eldredge. The Kindle book cost .99 and the the Audible version could be added for 10.49, even though it was in the "$3.99 or Less" section.
!. I bought the kindle book but before purchasing the Audible narration, I called Amazon.
2. I mentioned that the title was listed in the "Add Narration for $3.99 or Less" section but that the narration came up as 10.49. I asked for the lower price.
3. Amazon rep gave me promotional credit to buy the Audible narration (10.49) and suggested I also call Audible.
4. Called Audible and explained the story again. Audible rep added 1 credit to my account to use for the narration for the kindle book I purchased.
Hopefully this works for you!
Note: You will need to spend some money on this deal but some of the kindle editions are still pretty cheap. Here are links to the cheapest kindle editions (.99) I found that have the most expensive audible narration add-on (over 10.00)