[robocat]

> I doubt a mass produced thermostat that could get a price from the internet would cost more than $10

Total costs will be low if you can also find a perfectly spherical plumber (& electrician (& WiFi/4G-technician)) that charges less than $1 per hour for installation.

[WalterBright]

Amazon offers quite a smorgasbord of thermostats you can install for your home.

Obviously, nobody buys them.

[robocat]

In New Zealand the law and insurance requires that only registered electricians can work on household wiring, with paperwork per house to confirm. Surprisingly enough most people are unwilling to do something illegal, that will also void their house insurance.

Perhaps the laws and insurance rules are less strict where you are?

I also think that very few people feel comfortable working on household wiring, and very few people are comfortable with fixing plumbed in appliances.

I will add that the law is good, because houses get sold, and wiring is invisible, and no future owner wants to find out their wiring is bodged up by some clueless software engineer.

There is some truely terrifyingly dangerous wiring done by amateurs.