Being an NFL fan, no matter what team you support, is not cheap! OnlineGambling.com has put together a calculator of what it will cost you to see a game. They took into account a bunch of different factors: how good your seats are, parking, what you'll eat / drink at the stadium and if you're getting something from the team store.
You can try out the calculator here.
And you might also want to look for a second job after figuring out how much a game will cost you. Good Lord!