By doing SEO you compete against the rest of the Internet. In the event that you have ever asked why some of these sites rank higher than the others, then you should realize that it is a result of a capable web marketing procedure called Search Engine Optimization (SEO). SEO requires more investment than other areas of marketing (at the beginning). Since SEO takes a long time to show results, the majority of SEOs ask for a minimum 3 to 6 months commitment.
There will always be businesses in your niche or industry who have more resources and can afford to spend more on SEO related activities.