Comics, hugely popular in print and on the Internet, are still fledgling in the mobile space. The problem was not in the interface, but in the fact that the two major comics publishers, Marvel and DC, had yet to produce an iPhone app for their brand.

Today, Disney-owned Marvel is the first of the two to get in on the iPhone action. At the moment, you can buy five comics from Marvel’s X series of titles for $2 each. The titles include Joss Whedon’s Astonishing X-Men, Captain America, Marvel Zombies, Z-23 and X-Men: Age of Apocalypse.

Some, like Charlie Sorrel over at Wired, complain that the $2 per issue price is too high, with the print version costing just $1 more. Perhaps a subscription model with a much larger offering of comics would work out better for Marvel, though subscription models aren’t necessarily ideal.

Over in the music space, RealNetworks’ Rhapsody was hoping that mobile apps would boost Internet subscriptions, but the app was downloaded mostly by non-subscribers just checking out the service, reports Paul Bonanos at GigaOm.

But in the music space, free music streaming services make a paid model hard to compete. Comic books are a different game entirely. There’s no iComics store, nor is there a way to get those comics for free, well, legally anyway.

Another option Marvel has is to use advertising alongside its comics to bring down the price of the app. Besides promoting upcoming Marvel films, there is the opportunity to selectively target comic book audience via marketing in these apps.