So far, I've successfully created one campaign with 0.01$ CPC which lasted about a month (it had around 11% CTR), but I can't replicate it. I have had many other campaigns since then and some of them even reached 13%-14% CTR, but they costed me like 0.04$-0.07$ per click. This means than my other campaigns costed 4-7 times as much as my previous campaign, even though it had a better CTR. So is there anything else I can do besides CTR to decrease my cost? According to Facebook Help, the ad costs are determined by auctions, which means saturated target audience will cost more. By that logic, I should broaden my audience. But by doing that, it would decrease my CTR. Are my campaigns a lost cause even though I managed to get 13%-14% CTR?