Facebook fans have value.  But I hesitate to trust any studies that quantify a universal value equation.

Facebook fans has value.  However, the actualization of the potential value of a fan will define their actual value.

There are four layers of value in having fans:

1. Core Equity
2. Distribution Equity
3. Network Equity
4. Targeting Equity

Core Equity

Best case scenario, your fans are really interested in your product as well as your content/conversations.  These fans will engage with your content pretty regularly, or at least often enough that Facebook deems your updates relevant enough to display in their News Feeds.  The value of these fans relates to both their value to your brand as an engaged customer, as well as their value to the community as a participant/contributor.

Distribution Equity

Distribution Value is nothing to belittle.  This equity falls into two categories. 

(A) Incidental Distribution: When a fan engages with content or in conversations on your page this activity will be visible to their relevant social circle, increasing the organic fan growth and media-type exposure opportunities.  

(B) Purposeful Distribution: The nirvana of creative is to inspire fans to share with and recruit friends.  This active decision to share drives strong relevant growth.  This is advocacy.

Network Equity

It's not a fan until a group of people are doing it.  As more people participate in or join a community in a socially visible manner, their friends become more likely to join.  If I see an item in my News Feed that calls out that my buddy Joe joined a brand page and 20 of my friends are also fans I will be far more likely to join.  This isn't just because I respect Joe's opinion, but because I feel like my friends are all in on it.  This concept also works for Facebook ads.  When I see an ad that many of my friends have Liked, I will be more likely to Like it.

Targeting Equity

At the lowest end of the funnel, lies Targeting Equity.  As a marketer, I can target Facebook ads to existing fans or even friends of fans.  This provides real value to remessaging efforts as well as fan growth based on Network Equity.