GCFI/power failure alarm device?

[Delphinus]

Does anyone use any kind of device that emits an audible alarm in the event of a power failure?

It seems to me this could be useful in the event of a GFCI trip, i.e., if it happens when nobody is near the tank(s), it will draw your attention to a situation sooner than might be otherwise.

I imagine greenhouses, hatcheries, aquaculture, agriculture type operations must have a need for this so I bet there are a multitude of options available. I guess I'm just curious if there are any gearheads here who have this themselves and what devices they use? I did a cursory google search and came up with a bunch of options ranging from $40 to $100 so far. I wonder if that's pricey, or not.