Like Mad Men? Well, who doesn't, really. It's consistently been a ratings leader for AMC, and perhaps single-handedly transformed the channel from "It's like Turner Classic Movies, but with lots of commercials" to "That channel with amazingly good original programming." It's also really expensive to produce, however, and it's looking like AMC might wind up paying a fair bit more for season five when it starts production.
The issue is that creator Matthew Weiner's contract is expiring with Lionsgate, and Lionsgate (which produces the show) also has a contract that's expiring with AMC. In order for AMC to bring back the show, they'll have to increase the per-episode fee that they pay Lionsgate (currently north of $2 million an episode), while Lionsgate will have to give Weiner a raise, as well, since he's asking for more money. (Well, technically, they could just replace Weiner with someone else, but that'd be a risky maneuver, to say the least.) The ratings for season four were up 25% over season three on average, though, so they'll probably have good reason to request more money.
Even though Mad Men consistently wins Emmys and Golden Globes and myriad other awards, and has certainly placed itself among the most-talked-about shows of the past few years, it's always worth remembering that its total audience is pretty small change compared to network dramas. Its season four premiere pulled in around three million viewers, compared to around 23 million for the last episode of NCIS. Still, the cachet granted by the show's appearance on their channel, as well as the buzz it generates, probably makes it worth the money for AMC. Unless they solidify these deals, though, we could have a long wait for another season of Mad Men to come along.