Came across this this morning and thought it was noteworthy: Marvel editor Tom Brevoort posts Marvel's direct sales figures from April 1984 at his blog. I really don't know exactly what it says about the difference between the current market, and the one back then, but some similarities and differences are both quite glaring. Then, the top books like SECRET WARS and UNCANNY X-MEN were selling pretty much the same as modern counterparts like CIVIL WAR or NEW AVENGERS do now, only then there would have been sale or return figures on top of direct sales as a sizeable bonus, maybe three or four times as much I'd guess, though Brevoort claims these precise numbers are lost in time.
The real difference is in the mid and low-ranking books. Books near the bottom of the charts would these days be regarded as minor hits (eg THE NEW DEFENDERS #134, a truly abysmal comic, ranked at 21st of the 39 comics Marvel published that month, sold 62,700 copies; POWER MAN & IRON FIST #108, at 35 of 39 titles, was still selling 36, 100 copies). Interestingly, Marvel's creator owned comics from then, such as Epic's DREADSTAR (by Jim Starlin) and COYOTE (by Steve Englehart) way outsold Marvel's current creator owned books from their Icon imprint. Hell, Carl Potts' ALIEN LEGION was Marvel's 11th selling book, at 85,950. Even a master hyper like Brian Bendis can't get POWERS up to that level (though I'd put money on Mark Millar and John Romita Jr's KICK-ASS eventually hitting or beating those numbers).
That list has science fiction, fantasy, and even a historical title (AMAZING HIGH ADVENTURE #1, in with a bullet at 25th, selling 52,950), all doing great numbers. Certainly makes you think that Marvel's current line up could do with being more diverse, eh?