What’s a Facebook fan worth? $136.38.

This just in from eMarketer, a Facebook fan is worth $136.38:

Digital consulting firm Syncapse and research company Hotspex have come up with an empirical formula that puts an average value of $136.38 on the Facebook fans of the site’s 20 biggest corporate brands. Most of that value comes from how much the fans will spend on the brand’s products, with additional dollars coming from customer loyalty, recommendations and earned media.

Now, obviously, that number’s a bit of a fiction — the actual dollar value to your business is going to depend on the average value of your customer and other factors.But there are two interesting things about this study:

1) Fans spent about double what non-fans spent across all surveyed companies. That’s good ROI.

2) We’re starting to develop good methodologies for measuring the full impact of social media on companies’ bottom line.