PPC for Organic SERPs?

A new Model

[McMohan]

Recently I was asked by a prospective client, about the possibility of modelling the Organic SEO pricing in the lines of a PPC model. There will be a predecided list of search engines and any traffic that comes in through these search engines will be charged on a PPC model. There will be a tracking system in place ofcourse.

Given that, this model directly motivates one to get competitive keywords high-up for want of traffic, I for one am interested. What am I not sure of is how much to charge per clickthrough and should the price vary with keyphrases. Any thumbrule on this and experience will be really useful.

Thanks

Mc

[makemetop]

Normally we calculate an average rate per theme. We do this by looking at the primary search term value on Overture and then a basket of the next 50 or so most popular terms for the same subject. This often works out at about 30-40% of the top Overture PPC rate.

We don't vary price between keywords but do between different themes/subjects.

[McMohan]

Thank You makemetop. It answers my immdeiate doubt, but leaves me with few more. I am in a trickier situtation. The search terms are country specific, for which I can't hope for a lot of traffic to come through. In overture those country specific phrases are nor bid for, nevertheless work is needed to get those keywords ranked.
When such is the case, does it make sense to sign-up for such a deal? If yes, for what price per clickthrough? Is there a bottomline price?

Thanks

Mc