Do you have backend layer or your device is directly consuming the Facebook API?
I'm asking because with an intermediary layer you could provide different types of counter. In a few seconds, I could be able to choose from different sources of data for the counter. Through a simple web interface hosted by you.
Uses would becomes unlimited. Twitter followers, Foursquare checkins today/this week,...
Even number of kilometers traveled with runtastic as an example,... At max 100€ people could buy one for their home. More like a moving/interactive object for decoration. This market is potentially bigger.
I didn't found the price too high for a prototype.
And +1 for the NFC tag!