We’re not big fans of buying ads for a Facebook Page through “Promote Page”, at least for our own business.
We just went through this and although we did pick up some “Likes” for our business Facebook page, it didn’t seem like they were part of our marketplace. Promote Page doesn’t allow for a lot of customization of your ad campaign outside of location. Our page was most often liked by people who seemed to rarely add their own posts on Facebook, who didn’t seem to have any connection to the web development industry or have a business or organization that would lend you to believe they were looking for one, and most strangely (or not), tended to have liked hundreds and hundreds of Facebook pages.
Plus you really can’t customize the content of your ad in Promote Page.
But the real concern is the quality and the value of the Likes. It’s a pretty cheap ad purchase (you can pick your price, but we just went with $5 per day) but it does not seem to be worth even that price for us – a business promoting itself. For a campaign, particularly a campaign looking for interaction on posts, the results may be better.