Attendance is definitely down at Wrigley Field, but an average of 33,000 isn't really dismal, despite what the Tribune and Sun-Times like to pretend. Dismal is what the White Sox draw - over 10,000 fewer per game.
If you can get a rooftop deal for $75, I'd grab it, but you can get tickets in the ballpark for many dates for less than the original face value on Cubs.com (with dynamic pricing) or Stub Hub.