Quantity   Component name
1 × ESP8266 Serial Wifi Module Circa $4.50 from AliExpress. Mine is a version 2 (115200bps, firmware 90)
1 × Arduino Mega 2560 I used an "Inland" brand clone ($20 from Microcenter)
1 × Bi-Directional Logic Level Converter Breakout Board Sparkfun Part # 12009 - $3
1 × 3.3V Power Supply The WiFi module draws too much currentto power it from the Arduino's 3v3 pin.