There is this tiny ESP8266 WiFi module which can be bought for ~$2. There are projects on Github as well that can turn this cute little module into a big devil (example).
I wonder what is the efficiency of WiFi deauthentication attack performed using ESP8266? Does it work at all? If yes, does it work all the time? Are there networks which are vulnerable and others that are not (and how popular is IEEE_802.11w-2009 nowadays, what are the estimates for upcoming years)?