Writing original SEO content to get traffic to your site is more cost effective then paying per click.

SEO Copywriting v. Pay Per Click (PPC)

Search Engine Optimization (SEO) copywriting and Pay Per Click (PPC) are two advertising tools businesses use to drive traffic (and customers) to their website. While the goal for both SEO and PPC is essentially the same, the two methods are very different.

Search Engine Optimization (SEO)

SEO Copywriting is the process of writing text that improves the number and quality of visitors ("traffic") to a website from search engines through search results.

SEO Copywriting is Important

Original Web copy gets your Web pages viewed when Web users search at AOL, Google, or Yahoo.
Use of keywords or phrases in the content on a page (search engine spiders "crawl" pages looking for keywords).
Density of keywords used in your articles gets your pages recognized and ranked.
Writing interesting content that drives consumers to your Web site.

Pay Per Click (PPC)

Pay Per Click is an advertising model used by search engines and content sites in which advertisers only pay a host when their ad is clicked on by a user. Businesses typically pay a host on a flat-fee model or bid-based model. Pay Per Click is:

the placement of ads with a PPC provider such as Google AdWords, Yahoo! Search Marketing or Microsoft adCenter.
payment to a host each time an advertisement is clicked on by a user after appearing on a page.
possible abuse of clicks by competitors and web developers. Search engines are now implementing safeguards against such corruption.

While PPC can drive traffic to a site, it can also be costly compared to hiring a firm to develop well-written content that will appear on your website and naturally increase your page rankings and visitors.

References

http://www.brickmarketing.com/what-is-pay-per-click.htm
http://en.wikipedia.org/wiki/Pay_per_click
http://www.wellwrittenwords.com/pay-per-click-v-organic-seo/