Last week Amazon announced Voiceview for Kindle, an accessibility feature for blind and visually impaired Kindle owners. Voiceview is accessed through the Kindle audio adapter, which comes bundled with a $140 Kindle Paperwhite 3 and a $20 credit.
Or, you can make your own audio adapter for less than $5.
Early tests by AlleseBook.de and other sites have revealed that the Kindle audio adapter is really just a generic USB audio adapter with a microUSB plug on one end and a headphone port on the other.
You can make your own, and it will cost you anywhere from $2 to $10 to do so.
You'll need to get a microUSB to full-sized USB adapter, a USB audio adapter, and a pair of headphones or earbuds (which you should already have).
If you buy them on Amazon, the pair of components will cost you about $5 (for the audio adapter) and about $5 (for the USB size adapter). Or, if you don't mind waiting for a few weeks you can find the both components on Ebay for under a buck each (audio adapter, size converter).
Once you have the components, all you have to do is plug them into your Kindle and the Voiceview for Kindle should work automatically on the Kindle Oasis, or the latest Kindle Paperwhite.
If you have a Kindle Voyage, you'll need to download the TTS voice from this page on Amazon.com. It will come as an update file you can install on the Voyage, and once you've done so Voiceview should work just fine:
As far as other Kindle models are concerned, the latest official word from Amazon is that the $79 basic Kindle will not be getting this feature. Amazon's Peter Korn told The Kindle Chronicles that Voiceview for Kindle requires 512MB RAM, while the basic Kindle only has 256MB RAM.
The next basic Kindle model, codenamed "Woody", should have this feature, however.
P.S. You should keep in mind that VoiceView for Kindle is designed specifically as an accessibility feature. There's no way to turn on just TTS and have your ebooks read to you. When you plug in the audio adapter, both the audio navigation and the TTS is enabled. While that can be a bit frustrating for Kindle owners who have no trouble seeing the screen, let's not forget that this is not designed for them.