We put in a Champion UltraCool evaporative cooler a few years ago. Last week it kept the house at 77 degrees when it was 113 here in Southern California and running it full-time only costs us about $20.00 a month. Of course we don’t run it full-time or the house would get too cold. We have friends that have A/C and don’t run it unless it’s over 105 because they can’t afford the bills!
When we built our house in ‘01, we specified a ground source heat pump. Our power bills go down in the summer because the AC is essentially free.