Even from small vendors, people will be like "psh, $50/100/200/300/400/500 for THAT?, someone could make that from an ESP32 and (whatever 1-5 additional primary components)".
And yeah. You might be able to buy the PARTS for that much. Or half that much! Or less!
Usually the "cost of parts", known as the "Bill of Materials", is generally SUPPOSED to be less than 1/3 of the retail price. But the thing is, if someone is selling it to you (I'm not even counting kickstarter shit!), you can buy it NOW. And it will Work.
The rest of the money? It goes to crazy overhead, like "paying the people who designed it", and "making it do cool new stuff in the future", and "making it legal to sell to people", and "replacing your device if it shits the bed".
Like, it's no wonder we don't have random, cool, niche products. They will inevitably be:
- Shit on by people who weren't going to buy it anyway
- Cloned and copied, because duplicating a working system is easier than coming up with it in the first place.
See cool new things for sale that didn't exist before? Buy them! Or don't! Just don't devalue other people's work. It's a bad look. People building cool shit are not generally trying to scam you, they are trying to actually make a living. Most of them don't, and go out of business, making something they really cared about.