I would take a close look at the just released TI CC 3200: http://www.ti.com/tool/cc3200-launchxl http://www.ti.com/tool/cc3200-launchxl For $8 qty/1 you get:

I would take a close look at the just released TI CC 3200: http://www.ti.com/tool/cc3200-launchxl http://www.ti.com/tool/cc3200-launchxl For $8 qty/1 you get: WiFi radio and IP stack and an 80Mhz ARM Cortex M4 with 200k of flash for your application. TI has great documentation and example code along with a dev. board for $29