I'm just talking about a normal bathroom fan you turn on when you want to have a shower or something. I've honestly never seen one at a hardware store that cost

I'm just talking about a normal bathroom fan you turn on when you want to have a shower or something. I've honestly never seen one at a hardware store that costs more than about $40. An electrician would take about 15 minutes to install one if you've got a power source nearby, or if you get one with a light built in you could install it yourself by just replacing an existing light fixture with it. Luckily I don't have the misfortune to live anywhere near California, but that humidity sensor business sounds bizarre. Is that some kind of building-code thing?