We don't even have to be that shady about it. You can go as far as saying that if you donate, for instance, €10 towards the running cost of the event then you will be given free entry to it. Once the €10 comes from beoir members it should be classed as Beoir money and can be used to organise the invite only event. If it comes from non members on the other hand then it would be classed and an entrance fee.. All you have to do is ensure that everyone than contricutes is a beoir member