Even if the average actual fee is half that (everyone coming is a student), that's still decently into 6 figures, blowing any VAT threshold. It's probably just as well that these monies do not flow through our accounts, since they dwarf our other amounts quite considerably.
 We have an arrangement with a professional conference organiser. We say "we want this and this speaker", they do the actual logistics, pay the speakers fees and expenses, hire the conference facilities, etc etc. We get a conference at much less per day than a standard conference would be, while having world-class speakers, and they get to make a nice little profit with a lot of credibility in the conference world.