Once a year, in the period around Amazon Prime Day, you can extend or buy a new Kindle Unlimited membership at a great price. The extension periods are 6, 12, and 24 months. The downside is that you pay now. But the discount is worth it for me.
The usual monthly fee is $9.99. If you choose a 24-month extension, the monthly rate drops by 40 percent to $6, less than the cost of an ordinary Kindle ebook.
The easiest way to get to the page with the sale is to go to the Amazon home page and type in Manage Kindle Unlimited. You may have to link to yet another page but you’ll get there.