Around 10% of your Facebook fans is reached by an ad, imagine the positive and let's say 10% of these people click on your ad, and 10% of these clickers is actually triggered by the CTA and buys something. That would mean that 0.1% of your audience makes up for your costs. Providing your click cost you around €0,50 (Q2 2015 average), having 10.000 fans, the 10 buyers will cut €50 off your margin. That's €5 per buy. Question: is your product still profitable?