It's an idea. It also gives me less risk. If I buy massive amounts of beer and only 20 people show up, I'll have beer left that I'll never finish. 
How about everybody on the list has to confirm once more they are coming, like in the last week of March and I'll buy beer for those. 3/4 beers per person.
We probably go by bus anyway, cuz I walked to the Brabanthallen yesterday and it's actually a bit further than I thought from my house. I'm almost certain there will be free busses from the train station to the venue, so it's easy and fast to use those as well.

How about everybody on the list has to confirm once more they are coming, like in the last week of March and I'll buy beer for those. 3/4 beers per person.
We probably go by bus anyway, cuz I walked to the Brabanthallen yesterday and it's actually a bit further than I thought from my house. I'm almost certain there will be free busses from the train station to the venue, so it's easy and fast to use those as well.