You would be shocked at the huge population of the world that takes place in promotional contests. It does not usually matter how small the prize that is being offered is, people usually still take the time to participate in these contents. As a business, you can take advantage of this to direct the free likes to your social media pages. The contests usually also work very well to market businesses and thus apart from just getting the likes that you are looking for you will be able to grow your market share.
Once in while run contests to popularize your business; make sure that the contest are widely publicized and one great way of doing this is be ensuring that they are being run by prominent personalities. For instance you can have popular radio personalities run the content for you. As a requirement for participating in the contest, let people know that they will be required to like your social media pages. You will be shocked at the large number of free likes this move will get you within a very short time.