Facebook Ads work pretty well considering the huge targeted traffic and could also put holes in anyone's pocket if not driven with caution and proven techniques likewise any other Pay Per Click advertising.
In Facebook advertising, you need to bring your ad bidding low and save money by targeting and narrowing your ad bidding on Interests, age, and likes. Target people with similar likes and interests in your niche. Avoid targeting broadly or by it's default that normally shows you huge number of people(audience) in millions you may be reaching.
The more you narrow your ad targeting even to about 20,000 to 50,000 audience the better targeted results you'll get with low bidding less than $1 depending on your Niche keywords. Then tweak and test between CPM and PPC or use both campaign. Put track to your ads to know how far well they're doing. It's amazing how putting this to work will save you lots of money with great results. https://hubpages.com/business/Facebook-Advertising