Amazon might give readers something to get really excited about: A digital ebook and audiobook subscription service that provides Kindle users with all the content they can consume from a potential library of over 600,000 titles for just $9.99 per month. That’s according to this cached link, first spotted by GigaOM.

This ‘Netflix for ebooks’ would compete with existing services including those from startup Oyster, but would obviously have more depth and weight behind it thanks to Amazon’s existing success with the Kindle and its extensive user base, as well as the size of its library. The test pages don’t contain any publishers from the so-called big five, which include Simon & Schuster and HarperCollins, both of which do offer their titles to Oyster.

The biggest publishers ask for a large (read: at least seven figures) up-front fee, and services have to pay each time a user reads a book, plus new releases are kept for traditional sales methods. Amazon is likely looking for a better deal from publishers, or for greater access to current titles, which could be why they aren’t included in these test pages.

Amazon’s big advantage here could be its offering of nearly 8,000 titles in Audiobook format via its Audible acquisition, with Whyspersync for Voice functionality. These are listed on the sample page, and would allow users to switch between their ebook and audiobook versions of the same title fluidly depending on their location and situation.

The Kindle Unlimited feature would represent a new strategy for Amazon, too – it would be a standalone offering for a specific media vertical, presumably untethered from Amazon Prime. Amazon has thus far kept its subscription media business (Instant Video, Kindle Lending Library and Prime Music) as part of the overall value proposition of the $99 annual Prime fee – breaking out Kindle Unlimited as its own thing stands to generate more revenue, though, with one of Amazon’s most active and engaged audiences.

We’ve reached out to Amazon for comment, and will update if we receive more information.