Are you concerned at all that these black hat marketing strategies could cause you to be penalized so badly that it will be hard to recover? It's like Russian Roulette. You may get caught and then you may not, but you are right... it is getting harder to "game" the engines.
I also don't think seeing large number of followers will encourage other people to follow. Granted, it looks better to have 300 followers than 10 but if you're putting out fabulous content then you will eventually earn the followers.
Also Facebook just changed their algorithm again so if your engagement is poor, FB will show your content to fewer and fewer people. So if you buy FB followers that are low quality then it will be a waste if most of them never see your posts anyway. And since these followers are not going to be targeted you're just throwing away money in my opinion.
At the end of the day, it's better to have 50 Facebook fans that found you because they are interested in your niche than 5,000 that you paid for who will never be interested in your content and hurt your overall "Edgerank score" and engagement.