Interestingly, I did this for an event hosted by a student organization at my small university (~3,000 full-time students) last spring. According to the campaign statistics, CA$10.54 bought an astonishing 101,937 impressions. This is somewhat less impressive when you consider that we were paying by clickthrough to the event page, not by impressions, and only got 43 clicks, but due to the size of the university, I think almost every page view that whole weekend had an instance of our ad.
Edit: I feel I should clarify that last remark for those not immediately familiar with Facebook, or those who use ad-blockers: yes, of course there were a whole lot more than 100k page views that weekend, but our targeting was perhaps a bit too constrained (~1.1k users targeted out of a hypothetical 3-4k applicable), and on top of that, Facebook only reloads ads when you perform “serious” navigation, not just AJAX-based actions available directly from the news feed.
Edit: I feel I should clarify that last remark for those not immediately familiar with Facebook, or those who use ad-blockers: yes, of course there were a whole lot more than 100k page views that weekend, but our targeting was perhaps a bit too constrained (~1.1k users targeted out of a hypothetical 3-4k applicable), and on top of that, Facebook only reloads ads when you perform “serious” navigation, not just AJAX-based actions available directly from the news feed.