I don't think buying likes is a good idea. Buying likes results in "fake fans". Fake fans will not be engaged in your posts. It is better to have fewer fans who are more engaged.
Continue to post quality content.
I would also recommend determining which posts have received more engagement and Boost them. This way they may get more Shares. When people Share, they will be shared with people who no not currently fans, then they may become fans after they come across a post that was shared. Good luck, I'm struggling with the new algorithms myself.