Yes. Most events would have 1-2 (out of maybe 50 or so that showed up) that were new and we'd ask them how they heard about it. Most was from word of mouth, a small amount from Facebook and I don't remember anyone saying it was because of a flyer.

Though one thing I don't remember asking was whether "Facebook" meant Facebook ads or the other strategy for promotion on Facebook: create an event, invite everyone and tell all those people to invite everyone else.

If you spend $25 to advertise on Facebook and get just one conversion (new event attendee in your case) that wouldn't really be effective advertising at all unless you would be making at least a $25 profit from that conversion (not including the advertising expense). I realize that in your case you aren't out to make a profit, but you can see how from a business standpoint advertising on Facebook makes no sense in this scenario for most products.