As it's always repeated on here, don't go the Stubhub route. They jack the prices up big time over there.
I was in Boston last summer and just walked up and bought some tickets for 2 different games against the Twins. There's always people looking to sell prior to game time. One of my friends was there back in June and got a $90 face value ticket that was like 4 seats away from Pesky's Pole for $40 about 5 minutes after the game started.