you could try stubhub.com, and they usually have some day of game tickets, but for Cubs-Cardinals i dont think they would, and if they did it would be standing room only. A scalper or ticket broker also, if you like losing a lot of money
. Im looking at the game on the 10th on stubhub, and for 1 person, Sec 229, Row 4, its 40 bucks. For 2 people sec 240, row 23, 2 seats together for 55.99 each. You planning to go alone or with someone? Try stubhub.