Why is SEO important?
A website is only a website without proper Search Engine Optimization. To be quite honest the money spent on properly optimizing your website is well spent as on down the road it will be money that will not have to be spent on paying for keywords.
When you are looking for someone to provide a service for you what do you normally do?
In many cases you will go to a search engine and type in the type of work you want done plus the city you are in.
Example: Plumber, Zanesville, Ohio
This will produce 10 results on a page usually the top and bottom are paid ads and include the word ads, all others are non-paid listings which are achieved by optimizing your website.