I used to buy/sell tickets at ASU games when I was little. In '96, when ASU went through the regular season undefeated (starting with a huge upset over #1 Nebraska, BTW) prices were big. Games were sold out and prices were high, but supply was sometimes tough, which is OK, especially when you're a cute kid. I could make a few hundred before the first quarter was half over and once even upgraded my own seat to the loge plus ~$200. Always started with one extra endzone seat.
All depends on demand and demand depends on how your team is doing. BYU fans get so stoked so quickly I've always wanted to scalp out an awesome season. I'm sure we can't all be cheap;)