For this Monday night event, right now, it is £3 ($5.50). During university terms, Monday nights are reserved for students, hence a discount price. Next Monday is the first of the school year hence the deadline. Regular prices apparently vary from £6 ($11) to £20 ($36) depending on the event.
Ironic that they chose the Monday to pilot the scheme as it is this cheapest Uni night that they have the forged ticket problems with. At the end of year event in June, they had 2630 tickets handed in. Not bad as they only printed 2400. Thats what led them to think about this. Apparently that night was such a problem they had a fire officer threaten to close the place for overcrowding.