If only it was a question of fixed costs being divided by the number of participants, but bigger events have new and exciting fee schedules plus enough legal wrangling to make a grown man cry on the street.

You will find yourself on the hook for gigantic sums of money and paying horrifying fees for AV, room rentals, catering, insurance, registration staff, internet access, or to quote Blackadder: "stamp duty, window tax, swamp insurance, hen food, dog biscuits, cow ointment, the expenses are endless."