A Facebook Page can be a great way to build your fan-base, inspire engagement with customers/readers, and generally build upon your brand. However, if you want to do a promo on one, that'll cost you.
Facebook's policy dictates that one must get written approval from a Facebook account representative. In order to get one of those, you have to spend about ten grand advertising with the company, according to Eric Eldon at Inside Facebook.
So basically, if you don't want to violate Facebook's promotions guidelines, you can't really do any advertising or run any sweepstakes without actually paying for Facebook ads too. "You may not administer any promotion through Facebook, except that you may administer a promotion through the Facebook Platform with our prior written approval," that particular section of the guidelines states.
"The business model, with pages, is to try to get as many people using them as possible, then make a little money from each person if they want to do paid advertising — the preview fee goes against this model to try to keep Facebook legally safe," writes Eldon. "The problem, as many people trying to build promotions for Facebook have been discovering on their own, is that the fee requirement is never clearly spelled out. And, neither is the rationale for the fee. The result is confusion among marketers and developers trying to build promotions for Facebook, especially for small-business clients."
Well, if you stick to the classic advice handed down from a great many Internet marketing consultants, you'll want to use Facebook for engagement, and participating in the conversation. Using your Facebook Page to deliver a sales pitch has pretty much always been ill-advised anyhow.
That said, the lines can get blurry from time to time, and as Eldon notes, many businesses are still trying to figure Facebook out. Guidelines like this may not be particularly encouraging for them. They also raise questions about Facebook's future with regards to e-commerce, as Facebook continues to head in that direction (they're even taking PayPal more).
Facebook told Eldon that it doesn't have the resources to approve all possible promotions, and they all must be approved, so Facebook isn't held liable for illegal promotions.