Why can't I place online advertising myself?
Some of the search engines try to convince you that you could place search engine advertising yourself. However, if you did that, and you wanted visibility in all places your prospects might find you, you would have to place advertising in all of the five major search engines (Google, Yahoo, Bing, Ask, and AOL), in addition to dozens of local search engines and portals, depending on your type of business and location. This might include Local.com, SuperPages.com, YellowBook.com, Insider Pages, CitySearch, and more.
For each of these search engines, you would have to choose hundreds of keywords (search terms), bid on each one of those terms, and then design numerous ads associated with those keywords. Finally, once you do this at each of the search engines, you would have to manage across each of them, to allocate your budget where you are getting the greatest response. You would then continue to tweak your ads and modify your bids based on the results you get. You would have to be knowledgeable about how to maintain a high 'quality' score on the search engines, since this affects the keyword pricing.
After you finish all of that, you would need to design appropriate landing pages to take the traffic to, if you wanted to generate the amount of response you would require to make online advertising cost-effective.
In a nutshell, if you had a very knowledgeable full-time employee (or more) to do this, yes, you could manage your online advertising yourself. But most local and regional businesses simply do not have the time, the knowledge, the tools or the money to make the kind of investment necessary to manage online advertising themselves.