Facing what looks like a tablet tsunami and already feeling stiff competition from Apple's $499-$829 iPad, Amazon Thursday pushed its purpose-built black-on-white Kindle e-book reader into the mass market by announcing two comparatively cheap next-generation versions of the dingus.

Having started at $399 in late 2007, it's now offering a $139 model fitted with Wi-Fi to download books and a $189 model with 3G as well as Wi-Fi.

The $139 model undercuts readers from Barnes & Noble and Sony.

Kindle, which previously depended on a cellphone network for downloads, hasn't used Wi-Fi before.

The widgets, which ship August 27, are lighter and thinner than their predecessors and are supposed to have sharper resolution, double the old 2GB storage and faster page turning. Four gigs can hold 3,500 books.

The new Kindles' batteries can reportedly last a month on a single charge if their wireless capability is turned off, but they're also fitted with an "experimental" Webkit-based browser à la Chrome and Safari. And, apparently unlike the iPad, they're supposed to be designed for reading in bright sunlight.

The older version of the Kindle, now also $189, is mysteriously out of stock.

The Yankee Group estimates the e-reader market will be worth $1.27 billion this year.

Amazon, which doesn't breakout Kindle sales, claims its e-book sales will pass paperback sales in nine months to a year. It's believed to have sold three million Kindles, which puts it behind iPad sales and iPad only came out in April.

To meet that competition Amazon is reportedly trying to develop a color touchscreen that's as easy-to-read as its current E Ink screen, but touchscreen introduce glare. So CEO Jeff Bezos told the Wall Street Journal that "For the vast majority of books, adding video and animation is not going to be helpful. It is distracting rather than enhancing. You are not going to improve Hemingway by adding video snippets."

Amazon's digital bookstore serves $9.99 books to iPad, iPhone and Blackberry as well as Kindle.