From The Wall Street Journal, March 9, 2011:

Move Over, Apple! My Tablet Cost $200

"A lot of people are likely to stand in line to pay $500 or more for Apple's iPad 2 when it goes on sale Friday.

I didn't want to spend $500 for a tablet computer. I didn't even want to spend $400.

So instead I went online and bought a brand-new tablet for a bit less.

The cost? Less than $200 ... and about 20 minutes of my time.

No kidding.

...

I bought a Barnes & Noble Nook Color tablet (for $190 plus tax from a temporary online promotion, down from the usual $250). And then I downloaded a very simple, perfectly legal software fix from the Internet that turned it into a fully functioning tablet running on Google's Android platform. The fix, known as a "rooting," unlocks Barnes & Noble's proprietary overlay. The instructions came via Ars Technica, a reputable site devoted to technology, and were pretty easy to follow."

Balance of article is here, but may require subscription.