It&#x27;s already $4 with the new ESP8266-EX from WeMos!<p>Full WiFi stack, 11x GPIO, Analog in, SPI, I2C, 80&#x2F;160Mhz, 4MB Flash, power&#x2F;flashing over USB, supported by the Arduino IDE, or just use the NodeMCU Lua firmware with modules for most sensors, displays, MQTT etc.  I&#x27;m having a blast with them right now.<p>(Edit: <a href="http:&#x2F;&#x2F;www.wemos.cc&#x2F;wiki&#x2F;doku.php?id=en:d1_mini" rel="nofollow">http:&#x2F;&#x2F;www.wemos.cc&#x2F;wiki&#x2F;doku.php?id=en:d1_mini</a>)