Hi. We've experimented with more than 300 different ad variations and targets on Facebook. We've achieved best-case $1.5/subscriber and we accepted ads that achieved $3.5 or less per subscriber. We eliminated more than 290 ads that did not achieve our 1.5 to 3.5 / acquisition goal.

We found that the factors that mattered most for achieving our ad goals on facebook were: 1. Targeting to users with specific likes/interests. 2. The imagery in the ads

FYI. Google ads have achieved best-case $7/subscriber so we stopped using them.