Pick a buddy in PIT who has a car and do the roadie with him.
OK, if you really want to fly, book the WN fare (assuming it's also valid on the 20th) and keep watching the US/UA fares. As long as you plan to fly WN
sometime in the next year, you won't lose anything.
But I'd first see if you can find another football fan in Pittsburgh and avoid the flights altogether. Better yet...a whole carload of guys - 'Skins tix are really not that hard to come by these days. I mean, it's the St. Louis Lambs in town - you won't have to pay anywhere near face value to get in.