It was lovely meeting a good range of people interested in books, publishing, stories (or any combination!) and we all talked about why a group of local writers had got together in the first place.
The Extravaganza is a good example of an event where one writer would not have done this on their own. (There are insurance costs, space hire to sort out, plus having to put your stand up and down again all on your own. It made far more sense for a small group of writers to do all this between them and share the costs as it made the event viable for us all. Not sure it would have been for any one of us).
Having said all that, we managed to spread the word about what we do, why writers group together to help one another and sold our books so it was a good event! Any writer thinking of banding together with others should seriously consider it. One other advantage was our stand ended up having a wide range of fiction on it from my flash fiction (From Light to Dark and Back Again) to romantic comedy to short stories set in our area to YA fantasy/time travel. (More details of these in my CFT post). The upside of this, of course, is it meant it was far more likely that at least some of our books would appeal to some of the people and this did prove to be the case.
Spreading the word is time consuming and you can never know exactly what will come from it but unless you do try to put the word out there, nobody will know what you do. So I agree with the old proverb that "nothing ventured is nothing gained". And having support from other writers, and being supportive in your turn, is phenomenally helpful when doing this. Good luck!