Comic books have made their way into a lot of grownup places, from the pages of the New York Times Book Review, where John Hodgman recently reviewed all four volumes of Jack Kirby's Fourth World Omnibus, to Philadelphia's Institute of Contemporary Art—currently hosting an R. Crumb retrospective—to Parisian art galleries. And of course, there's Hollywood. While no stranger to superheroes, Tinseltown is in the middle of an unprecedented love affair with all things comic. The year's top-earning movies are two superhero films, The Dark Knight and Iron Man, which have grossed $1.5 billion worldwide. Next year's most hyped film is an adaptation of the 1980s cult comic book series Watchmen.

But it's not just comic books and their cinematic adaptations that are big business; the market for comic art—the original pencil-and-ink drawings used to produce comic books—is in the middle of a boom that keeps moving into uncharted territory. "It hits a high point and then another and then an even higher point," says Albert Moy, a New York-based dealer who has been buying and selling comic art for over two decades. (See a slideshow of works that have sold or are for sale.)

While some insiders estimate the global comic art market to be worth $25 million annually, others say it's more like $70 million to $100 million. At the 2008 San Diego Comic-Con International in July, Joe Mannarino of All Star Auctions and Comic Art Appraisals in Ridgewood, New Jersey, did $1.2 million worth of business in four days, selling the Neal Adams/Bernie Wrightson artwork for Green Lantern No. 84 for $115,000—a world record for the artist, he says—and two oil paintings by fantasy artist Frank Frazetta for more than $451,000. Anthony Snyder of Anthony's Collectibles in New Jersey recently set a personal record when he closed a deal worth $150,000 for a 1964 Spider-Man page drawn by John Romita Sr. And dealers say the economic crisis hasn't yet put a damper on things.

"Gen X, the generation who grew up reading comics when the comic book artists were the stars, came of age and now have the disposable income to collect art," Mannarino says, explaining the market's dramatic rise.

But generational shifts don't fully explain it—geography plays a part too. According to dealers, European collectors have been driving up the price of comic art for the last two years, aided by the strength of their currency. A European collector can pick up the cover art for Fantastic Four No. 171 from 1976, penciled by Jack Kirby and inked by Joe Sinnott from Moy's website for €23,809 instead of the $35,000 an American would shell out. "They all want that Jack Kirby page just like everybody else," says Moy, who has customers in Italy, France, Britain, Spain, and Greece. "Half of the stuff I send out on a weekly basis is to Europe," Snyder says.