Tickets bought on the day?

Hi love reading the threads on here but never posted.Decided couldnt afford tickets for this tour because of stupid prices (affraid of heights so cheaper ones no good) but read last nights reviews and really want to go might even put up with heights.Wondered if tickets left on day do they reduce them nearer start time or stay full price, going down to London June 17th so hoping for then.The reviews have been great but still nothing like being there even looked on ebay but dont know who to trust.