Why should we do Search Engine Optimization when we can buy Pay-Per-Click ads. To be honest PPC is a great marketing strategy and can bring fast results for your campaign, but it will be more expensive to compete with your competitors. That creates price war that can diminish your ROI. Pay per click should ideally be done with SEO campaign, because close to 90% of traffic is going to organic first page results and that is the place where your money is.