I don't think there's any doubt that a TopTen SERP position will produce results that surpass those that PPC ads can provide. I'm also satisfied that the net cost of
SEO is less than the money spent on PPCs.
However, there's the problem -- and almost all of us accept that it exists -- that no-one really knows what the algos are nor if/when they're going to change. Posts here at WPW are constantly bewailing the sudden loss of position and repeatedly being met with a response "Who Knows Why?"
True, there can be a bad hat basis, but we expect this to catch up with the site and, for the present case, such "exceptions to the rules" might as well be ignored.
In theory, however, a site earns/achieves/deserves its TopTen position because of intelligent and sufficient application of
SEO principles. But if these keep changing -- as they do -- all thoughts of ongoing good organic placement and results disappear as quickly as the site in question. In acknowledgement of this, we're therefore advised to exercise constant monitoring and to have, as it were, Plan B ready at all times.
In contrast, PPC deals with knowns instead of unknowns. Sure, you need the right wording and the right choice of keywords but, if these are what they should be, a R.O.I. is just about a given. In effect, you pays your money and you'll get yourselves a fairly decent return -- and certainly one that's far more predictable, measurable, and analyzable than is the case with print and other media.
In contrast -- and if we're brutally honest about it --
SEO continually incorporates surprises and this is what most business people are determined to steer well clear of.
The economic case for
SEO can be made, but it can also be seen to rest on shifting sands. Even if PPC is more expensive, it at least has a more solid foundation.
Duncan