I've advised three different companies and brands in the past week that Facebook has one of the best ROI percentages for ad dollars spent. As a business page, Facebook only lets 6% of those who like your page see your posts in their News Feed. So pushing people to like your page without spending money to boost posts means you only reach a fraction of your following.
On the flip side, if you pay to boost a post or advertise on Facebook, you can target a very specific market and demographic, plus you get guaranteed views or clicks to your website. Even $20 - $30 can go a long way with a Facebook ad.
Now they made it even easier to manage ads for business pages with their updated / new (not sure which, but I hadn't heard of it before) app for the iPhone. Looks well designed and would make managing ads much easier than their website. Will share some thoughts on usability soon.