It's a must now... in the past week Facebook have introduced a new filtering system for Facebook page posts, only 15% of your fans are now notified of your pages posts. To reach all of your fans (like it used to) you have to pay $1 per 1000 fans reached. I have a page with 100k Fans and the posts reach 15k... or $100 to reach them all. A small page with 8k fans will cost $5 to post to 3k to 5k fans - $10 will reach all of my fans. Welcome to the new commercial Facebook.
I know these adds are cost effective but they yield much more from the investment so it doesn't matters.
If you can get your CTR up it can be super cost effective! I paid less than a cent for a visitor for one of my previous campaigns. And yes... the campaign made good money.