I recently organised a multi-author sale. Several authors (including myself) agreed to reduce the price of one or more of their ebooks to $0.99/£0.99 for a week. I created a page on my website listing the books with links to where they could be bought. Everyone agreed to promote the sale to their newsletter or pay towards a Facebook advertising campaign. So far so good.
I got an unpleasant surprise on the eve of the sale, when I went to reduce the price of one of my books to the required $0.99/£0.99. Amazon wouldn’t let me reduce the price to less than $1.99/£1.25. These minimum prices have been in place since at least 2017, but they don’t get talked about very much, so they’re easy to miss.
The book that I was trying to reduce the price on contains a lot of images, and the file size is about 7MB, much larger than the typical ebook. Kindle books of between 3MB and 10MB have a minimum price of $1.99, even on the 35% royalty option. Kindle books larger than 10MB have a minimum price of $2.99 on the 35% royalty option.
Most ebooks won’t be affected by this, but books with large numbers of images and ebook box sets might be. If you’re planning to run a sale, check the minimum price for your book before you publicise the sale price. In my case, I was able to work around the issue. Since I have multiple books published, I was able to simply put a different book in the sale, one with a file size small enough to allow me to reduce the price as required. This neatly illustrates one of the advantages of having multiple books published — greater flexibility.
The full details of the price limits for different sizes are on the list price requirements page at KDP Help.