Until September 15, you can sign up for three months of Kindle Unlimited for just $11.99. Regularly $35,97, Kindle Unlimited is Amazon's subscription service for e-books. This deal not only gets you three months for the price of one, but also access to over four million titles, thousands of audiobooks, and select digital magazines.

Since Amazon's subscription service was launched in 2014, the company says that three billion books have been read via Kindle Unlimited and that it has paid out over $3.5 billion to Kindle Direct Publishing authors.

Kindle Unlimited members can get additional months of the service for free, while new members can get 3 months for the price of 1.