I'm not sure about all of their titles, but with the Hellboy stuff, it was, not too long ago, 24 story pages for 3 bucks. Now it's 24 story pages for $3.50. That includes one-shots and mini-series. I always liked that, too. I'm getting 2 extra pages, for either the same price as a regular comic, of 50 cents more than a regular comic. And come January, it'll still be that way.
Just checked some others: Eric Powell's "Buzzard" mini series was 24 pages as well, for $3.50, and the main story was 18 pages per issue(3 issues), with 6 pages being devoted to a Billy The Kid's Old Timey Oddities back-up.
Powell's "Billy The Kid's Old Timey Oddities And The Ghastly Fiend of London" is 4 dollars, but with the same page count as Buzzard: 18 pages for the main story(per issue, 4 of them) and 6 pages for the Goon back-up. I don't know why this one is four bucks, but even so. There's still an extra two-pages that could justify purchase that you wouldn't get from a Marvel comic.
Their Metalocalypse book is also 4 dollars, but the total page count is 40 pages, with 22 pages of story. But there was also some "intro" to the creators. Dark Horse stuff has a tendency to fluctuate by a page or so sometimes(Billy The Kid #3's main story is 19 pages instead of 18)
The Metalocalypse vs The Goon one-shot was $3.50 for a total of 32 pages, all story, no ads.