This year in Chicago, buyers have been willing to pay only a 118.9 percent premium for a McMansion compared with what they will pay for a non-McMansion. In other words, McMansions, which should be more expensive because they are large, are selling for slightly more than two times the average non-McMansion. But in 2012, people were willing to spend far more for McMansions. Then, the premium was 145.5 percent over the typical non-McMansion.