My solution for this was an ESP8266-based Sonoff POW (wireless smart switch and power monitor), running Tasmota, sending data through MQTT to Home Assistant, scripted to send notifications through Telegram.
Interesting, I didn't know that Sonoff did a power consumption monitor. That makes sense for something like a washing machine. Presumably though you never actually use the relay/off-switch capability of the Sonoff, right?
The only time so far I used both the switch and the power monitor was on the Christmas tree, because I was curious how much it cost to run ($3 or so overall iirc).
