My friend who does a lot of business trips to Vegas told me that I should look for Half Price Shows on the strip, but he warned me that the newer Cirque Du Soleil shows probably wouldn't be offered for half price. To my surprise, he was wrong!
I stopped at two or three half price show booths on the strip, and I finally found one next to the 4-story M&M store that did offer Cirque Du Soleil! The attendants at the booth were very friendly and answered all the questions we had.
We ended up getting three balcony tickets for Zumanity about 5 hours before the 10 PM show the day of and were pleasantly surprised when we arrived and found out that our seats were towards the center of the balcony - very good view considering that we only paid $58 each for a show that normally runs over $100.
I didn't gamble much in Vegas, but I'd say that luck was working on my side that day.