Attendance at Big Sky games has gone down consistently since Boise State, Idaho and Nevada left the conference in the mid-1990s. There is no need for large gymnasiums anywhere in the Big Sky. Other than Northern Colorado, who started filling their facility when the Bears got hot earlier this year, nobody in the Big Sky is averaging near capacity for their current facilities.
BTW, I've watched Idaho State games at the Huntsman Center, Marriott Center and at the Taco Bell Arena in the last couple of years, and you want to talk about empty. Boise State drew about 3,000 fans in a 16,000-seat arena. Utah and BYU were both at about 8,000 in huge arenas. As weberdude notes, having a large, modern arena only 40 percent full is a lot less energizing than packing a 50-year-old, 2,000-seat gym.