What is the best way to purchase a Wrigley Field Chicago Cubs ticket the day of the game?

eBay and StubHub have been too pricey for this Saturday’s (6/16/2012) sold out Cubs vs. Red Sox game. I have never had to purchase tickets the day of game but I am going to try my luck this Saturday. Does anyone have any advice? What to do? What not to do? Info on scalpers? If I wait until the 2nd or 3rd inning, is it likely the sellers will lower their ticket prices?

I’ll be taking Chicago’s Red line this Saturday to Wrigley Field. Thanks in advance for your thoughts and help.