What year are we???
FB likes been around for a while now but not worth to much, don't get fooled. Best is you find an existing group or a few in the niche you are targeting and make an offer on buying the group. With that said make sure you check comments, consistence of post, the more shares, comments and likes the group as the more valuable it is. Still lots of people have good groups that do not know value and could use cash.