Late tickets for cheap?

I am a grad student so I don't have a ton of money but, does anyone know if there are usually any last minute tickets that become a lot cheaper for the games and where that would be? I am just as excited as everyone else this year and am trying to go to as many games as I can afford. This is of course starting with with Sunday's game with the Bears lol.

I just moved back into Houston and can afford to wait until the last minute to get tickets instead of having to plan for traveling.