There are many ways to define the 'value' of something for different purposes - however a value derived from comparison against a task which nobody would ever want to perform (employ millions of 'librarians' with grep) is not likely to be useful anything.

To give some examples of different kinds of value you could assess for a company like Google - Its value for its users (for early Google this would be basically how much value is gained by using Google as opposed to an alternate search engine) is for instance very different from Google's 'use-value' (how much money Google make from it), its market value (driven by a lot of speculation as to what Google's future might be, as well as its 'use value') and its 'liquidation value' (of assets - assumedly very low when Google began).

The link comes closest to looking at the value for users, however this would be better ascertained from a closer understanding of what Google was supplanting at the time (other search engines such as Altavista who had results which were poorer, but not hugely so) and then trying to derive some basis for how this might affect the 'user', rather than what the cost for Google might be to implement their search mechanism in a technology-backward way.

[edit] To clarify that I'm talking about valuing Google in its infancy (as per the OP) rather than Google at present (which is obviously more than just search) - thanks to martinced's comment below.