There are usually plenty of "scalpers" outside of the stadium. However, being the texas game, it might be a little harder. at the Memorial Student Center (MSC) there are some tickets sold for face value as the school tries to cut down on scalping. Usually there are some available depending on how early you get around campus. If you're around the West Campus Parking Garage, there is always someone selling tickets there. Also, there is a Budweiser tailgate that gives away free beer. I'm a Miller Lite man myself, but free beer, is free beer. Hope this helps.
Go to texags.com and look at the forums. There should be lots of ticket options there.