Potential upgrade from the ESP8266, only 1$ more and has loads more features.

http://hackaday.com/2015/07/13/new-part-day-the-esp8266-killer/

Seed has it http://www.seeedstudio.com/depot/EMW3165-p-2488.html
and a dev board http://www.seeedstudio.com/depot/EMWE3165A-Development-Board-p-2489.html