Actually , it is really hard!, if you can have a 1 post engagement in 5 reached, you can have low CPC but if 1 post engagement in 50 reached, it will start to cost you a lot. My advice is to make a Quote post , shareable image, then they will like your page then you will have now evergreen USA audience.I was wondering how to change my billing type from impressions to link click ( i uploaded photo ) and how to go to lower cpc possible for USA traffic