they have been at the half-price ticket places pretty frequently over the last month or so. not necessarily half off but in the 30-40% off range. it feels like they have been having a slump in attendance and are trying to bump up the crowds.
across the venetian at the fashion show mall they have a Half-Price ticket store location that you can check pretty easily, should you actually stay close to there. but the Half-Price Ticket stores are pretty spead out. You do need to check the day you are willing to see it though.
As for online finding tickets, im not sure.