DC Comics announced a new digital storefront in Apple's iBookstore this week, and for now, it's filled with Batman graphic novels. The graphic novels were already available in iBooks, but the storefront pulls them all together in one place. Of course, you can also buy DC's digital graphic novels via comiXology or DC's comiXology storefront, or from DC's Amazon storefront.
You might want to shop around a bit, though, because several of those books are cheaper on Amazon than in the iBookstore: Frank Quitely and Grant Morrison's Batman and Robin, Vol. 1, is $9.68 on the Kindle, $11.99 on iBooks. Frank Miller's The Dark Knight Rises and The Dark Knight Strikes Again are $9.99 on Kindle versus $12.99 in the iBookstore. There are a couple of more, and in each case that I saw, Kindle beat Apple, at least on price, and all were readable using the Kindle apps on the iPad and Android devices, so these digital versions are in direct competition with each other.
What's going on here? My understanding was that Apple's agreement with publishers who use iBooks is that they won't sell them at a lower price elsewhere. Of course, they may be easing back on that since the U.S. Department of Justice sued them, alleging price-fixing. Or maybe it's just a glitch.