Anything over a few pennies is too much to put on a bottle of detergent in the factory.

And putting it on at home is foolish - more work than just reordering detergent myself when it runs out.

The previous posts are presumably referring to the Amazon Dash Button: https://www.amazon.com/Dash-Buttons/b?ie=UTF8&node=106678980...

I use a Dash button in my bathroom to automatically order toilet paper.

It's great because I never remember to do that before its "too late", and its still MY CHOICE to press the button. Nobody wants individual toilet paper packages stuck with their own tracking devices, at least not now.

It's weird that articles like to push that idea, rather than more simple examples people might use.

People used to leave their empty milk bottles for the milkman to pick up. Could do the same with detergent bottlecaps.

Now THERE's an idea! Save a trivial part of the packaging of whatever you need to reorder, put in in a bowl by the garage door. When you go out, grab a handful. No list, no remembering, and super easy to do!

$4.99 says it is subsidized.

You are describing the end-user price of a device that includes batteries, a circuit board, a WiFi transciever, a switch, and an enclosure. If the BOM and assembly costs can be brought down to $4.99, that's a miraculous feat of engineering and modern civilization's economies of scale; if it can end up on your doorstop for that price it must be subsidized.

How else could that device cost less than the gallon of industrial chemistry that you order with it?

Yeah, I find it hard to believe this device could be sold for $4.99 at a profit, if you count up BOM, assembly and logistics related to sending it. But given that some posters mention Amazon actually gives you $4.99 back for the first purchase, they must not be caring.

Anyway, here's a teardown I found:

https://mpetroff.net/2015/05/amazon-dash-button-teardown/

Now a surprising thing that I didn't know before - this thing has a microphone on board. Yes. Yet another Internet-connected microphone. Apparently used only to configure the button via ultrasound, but I wonder how hard would be to repurpose it...

Check this out: https://www.aliexpress.com/item/ESP8266-ESP-12-ESP-12F-CH340...

$2.72 for a single programmable WiFi device, delivered for free. All you need after that is a cheap battery, button, and enclosure. The existence of the ESP8266 is changing the way I think about electronics.

> delivered for free

which is subsidized by the USPS and Chinese government using mail reciprocity agreements to ship for pennies.

https://www.washingtonpost.com/news/storyline/wp/2014/09/12/...

Why not a bluetooth SoC like nrf52832 or DA18586 and a esp32 for wifi-bluetooth bridge? The price is the same.

This way you will have months or even years in autonomy instead of weeks.

I don't know about that - I can pick up a ESP8266 dev board for under $5 individually on mouser - I feel like I should be able to get that cost down significantly if I am building millions. I am not an expert in manufacturing at all but it seems like I should be able get a small enclosure and battery for under $1.50 in high enough quantities.

It might be worth it as a funny gadget once. But not when you'd like to have 20+ of those in your house. Or one for every product that you order regularly.

Don't forget that you get that $4.99 credited back to your account on first use.

It is if you take into account the fact that the people buying one for a product are most likely going to buy more for other products too.

The very few people I know with them have 5 or more. That adds up. Especially considering you could just modify one to handle any number of products.