http://www.prosportsdaily.com/nfl/giants/
New York Times (registration required): "But the stadium was sold out, even if it was not close to filled, for a game that the Patriots ended up winning, 27-20. In the preseason, tickets sold mean more than the points scored, because preseason games account for 20 percent of a team’s ticket revenues. And ticket revenues account for about 30 percent of the N.F.L.’s total revenues, now more than $6 billion a year."
I think it's ridiculous that they charge regular price for Pre-season tickets. The starters don't even play but half the game for the most part. Most teams don't even let their star players play that much. Ladainian Tomlinson doesn't even take a single snap in pre-season.