ESP8266 SMT Module [ESP-12F] : ID 2491 : $6.95 : Adafruit Industries, Unique & fun DIY electronics and kits
ESP-01s WiFi Module - ESP8266 based
Wi-Fi adapter ESP-01S for MINI+ and MK4 | Original Prusa 3D printers directly from Josef Prusa
MakerFocus 4pcs ESP8266 Esp-01 Serial Wireless Wifi Transceiver Module
MOD-WIFI-ESP8266 - Open Source Hardware Board
Build a Circuit with the ESP8266-01 Wifi Module
Amazon.com: HiLetgo 1PC ESP8266 NodeMCU CP2102 ESP-12E Development Board Open Source Serial Module Works Great for Arduino IDE/Micropython (Small) : Electronics