[luma]

Check out the Sonoff S31: https://sonoff.tech/product/smart-plugs/s31-s31lite/

You get an ESP8266 micro with wifi plus a power supply, relay, momentary button, current and voltage sense, and a couple LEDs all for about $8. Serial debug and flash headers are broken out for easy access on the PCB.

They ship with chinese firmware but the headers and standard hardware make them dead simple to flash with your own firmware, or ESPhome or Tasmota if you prefer.

[kesslern]

I have had 4 of these running Tasmota for a couple years now. They have been rock solid.

[fragmede]

Boughted! Now to take them apart.