What should an e-book cost for a $25 hardcover?

Are people starting to value ebooks less?

Nathan Bransford asked people what they thought an ebook should cost if the hardcover retailed at $25? While the results are likely not up to a scientific standard, they are nonetheless interesting.

On June 14, 2010 people responded:

And the same survey ran again on February 2, 2011:

Source

Shop at Amazon.com and support Farnam Street