The Xiaomi DOCO ultrasonic handheld misting fan is now on Xiaomi's Youpin crowdfunding website with a price tag of 69 yuan (US$10). The portable fan has three power levels that can reach a maximum of 5100 rpm for those really hot days. The Xiaomi DOCO misting fan can apparently reduce the temperature around the user by 3 °C (5.4 °F) more than a traditional fan.
https://www.notebookcheck.net/Xiaomi-DOCO-ultrasonic-handheld-misting-fan-offers-up-to-5100-rpm-of-cooling-power-for-just-69-yuan-US-10.470721.0.html