Conventional marketing and advertising have their advantages & disadvantages. The bottom line with SEO marketing is that a well set up site can reap benefits (traffic) for a long time to come.

How does SEO compare to advertising and promotion in newspapers?

Newspapers of different kinds last as long as a day in most cases, and a little longer for some others.  This means that, not only does readership drop off as the newspaper ages, but when a new issue comes out you have to readvertise to  maintain  the momentum of your brand or product campaign.  This can be costly and time consuming.

How does SEO compare to advertising and promotion by Phone/Advertising Directories?

Advertising here is based around spending more money every year for the same publication.  SEO only charges once, in most cases, and the results last for a very long time.  In the cases however where competitors compete for your specific key word searches, then you can request refresher campaigns.

How does SEO compare to advertising and promotion by TV/Radio?

This is an expensive form of advertising in most cases which can often be forgotten depending on the quality and length of the campaign.  This type of advertising is often best used by medium to large companies to promote a repeated branding/sales campaign.  SEO can reach a vast amount of clients, and over longer periods of time, all at a fraction of the cost.