If you didn't take advantage of the recent price cut on Amazon.com's (Nasdaq: AMZN) Kindle, you may have to wait for your $189 e-reader.

"Temporarily out of stock," reads Amazon's website since late yesterday, with no timetable on its availability.

This isn't the first time that potential buyers have been denied.

When the original Kindle hit the market in 2007, the initial stock was depleted in a matter of hours. Weeks after Oprah Winfrey gave the gadget a mainstream push a year later, Kindle inventory zeroed out heading into the critical 2008 holiday shopping season.

Despite the implications of popularity, there were other reasons for the outages. Those who waited until the sixth hour to be early adopters in 2007 had to wait more than a week because of supply chain hang-ups. Those who ran into the "11-13 weeks" delay a year later eventually realized that Amazon was just waiting for the new and improved Kindles to hit the market.

It's different this time.

There is no timetable for when the Kindle will be back in stock. PC World got a hold of a representative at Kindle screen maker E Ink this morning; it is committed to increasing its capacity to help Amazon meet demand.

In short, this may be the first time in the Kindle's history that the devices are so hot that Amazon can't legitimately keep them in stock.

Clearly, this last price cut did the trick. Going from $259 to $189 -- a far cry from its original $399 price tag -- is a real driver. Amazon's hand may have been forced after Barnes & Noble (NYSE: BKS) slashed its Nook ransom, but it's working.

The further that Amazon distances itself from the $499 to $829 price tags on Apple's (Nasdaq: AAPL) iPad, the better.

Kindle buffs will argue that a longer battery life and glare-free screen are strong selling points for dedicated readers, but it's hard to compete against Apple's Swiss Army knife. Things will get even more competitive as cheaper tablets fueled by Google's (Nasdaq: GOOG) Android hit the market in the coming months.

If anything, this is where an outage can become problematic for Amazon. Time is ticking, and the last thing it needs is for impatient e-book readers to hop on to a rival platform.

Then again, Amazon would probably rather be selling e-books than e-book readers. The company warned that operating margins during the current quarter will be contracting, likely the result of robust Kindle reader sales at rock-bottom prices. If it could establish its Kindle store as the e-book platform of choice without the hardware investment, Amazon could go back to concentrating on its media roots. It has done its part to make its Kindle app available through a variety of smartphones, tablets, and PCs.

Unfortunately, the marketplace is getting too competitive, and it will be hard for any software platform to rise above without the installed base on the hardware end. Sony (NYSE: SNE) and Borders (NYSE: BGP) didn't dive into the price war to be accidental tourists. Everybody has some serious skin in this game.

Amazon is in too deep -- even now, when its Kindle inventory is shallower than shallow.

Is this as low as e-readers will get? Share your thoughts in the comments box below.