While the crowd for this past weekend's game against Wyoming was pretty pathetic, at least it was pathetic by 2010 standards. The average attendance through three home games is still above 40,000, and the surge of momentum within the TCU fanbase looks to pick back up the next two weeks as Amon G. Carter should be sold out for both the BYU and Air Force games.
If you're generally the type of person that waits until game day to buy a ticket at the door, I would recommend a change in your routine for the next two weeks. Based on what is available when doing a quick search online, there are very few lower-level tickets remaining for the BYU game and the best seats in the upper deck have already been taken as well. Good seats are even scarcer for the Air Force game, since the Falcons ought to be coming to town ranked in the Top 25 for the Frogs' homecoming.
So before you end up without a ticket, or having to pay way above face value to a scalper, go get your tickets ASAP online and be done with it.