Most search engine advertisers who employ both SEO and PPC typically report very positive results. However, it is important to understand that a well-executed SEO plan over time usually delivers more visitors at a lower overall cost than a PPC campaign, as SEO is a fixed-cost expense that can continue to generate revenue for you via good rankings long after you've finished paying for your campaign, whereas PPC is a variable-cost expense that can escalate beyond your budget at any given time and stops sending you targeted traffic the moment you stop paying for listings.