ESP8266 brought an inexpensive way to include Wifi in small DIY projects. Later SeeedStudio has released Linkit Smart 7688/7681 based on MediaTek chips.The MediaTek LinkIt Smart 7688 development platform consists of a Linux Wi-Fi SOC with the OpenWrt Linux distribution. Scargill’s Tech Blog has taken a look. Always good to have a few alternatives. The basic module starts at $5.
Also take a look at the MediaTek 7866 Developers Guide