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Review of ESP8266 powered by the Slant community.
MakerFocus ESP8266 ESP-01 Serial Wireless WiFi Transceiver Receiver Module 1MB SPI Flash DC3.0-3.6V Internet of Things WiFi Module Board.
Price is $12 for 4 pieces.
Read Getting Started with the ESP8266.
Read A $5 Programmable Tiny Webserver The Size of a Jump Drive.