Is there a cost per acuqistion figure I can quote that if I hire an agency to link build that we can guarantee a level of increased traffic from Google?

[Pday]

I am looking to justify to a pubilsher the cost outlay to hire an agency to do white hat link building for me as we do not have time.  (the site is fully optimised but we lack the inbound links our competitors have) - is there a way I can explain in terms of numbers ie page impressions that if we build for eg 10k high quality anchor text links into our site we will get x thousand more page impressions as our rankings in the search engines will increase?  Just need a justification before the budget is allocated.

[AdamThompson]

Unfortunately, there are no specifics any of us could give you in that regard. The results (number of visitors) you'll get from x number of links depends on many factors, including your keywords, onsite optimization, link quality, etc.

The best way you could estimate would be to take each keyword and determine:

How many exact match searches are their on Google for this keyword each month?
If we achieve a #X ranking, what CTR could we expect?

The answer to those two questions will tell you how many visitors you might expect from the keyword.

Then you'll need to analyze your competitors keywords and estimate how many and what type of links you'll need to achieve the ranking you want.

Together, that will give you a very rough estimate of how much traffic you might expect from your link building efforts.