I imagine that you could build a functional equivalent with an ESP8266, a power adapater, and a Twilio account - no server required, since you should be able to measure volume directly on the ESP8266 itself. The parts would cost you less than $20 - probably less than $10.

One that emits an ear-splitting siren if the noise gets too high? Much cheaper and more convenient than reporting to the owner. The kids will get the point pretty quickly.