[Geodata] What is the value of free data?

[Pat Cappelaere]

It is great to make geodata free.  However, we could get more of it if  
we could quantify the value of that data.
We need to justify the business case.

Interestingly, for opensource software projects, you can compute the  
potential cost of developing that software.
This is an approximation of the value of that code [but not the value  
that is enabled by the code]
So I am looking for a similar and still imperfect metric.

Any suggestion?

Cost of similar commercial imagery?
Economic value of imaged area?
Potential damage assessment (disaster)?
Scientific value of imagery?

How do we estimate this?

Thanks,
Pat.