Flic uses BLE (Bluetooth 4).

It also costs 10x as much as the regular BT buttons. Can't wait for BLE to drop to mass market prices.

When the ESP8266 successor, the ESP32 comes out you'll be set: https://www.sparkfun.com/news/2017

For now, you can always buy your own bluetooth LE modules and attach them to a small microcontroller, for buttons, you could make your own wall buttons with nice enclosures or go the ridiculous route: https://www.adafruit.com/products/1185

I made a WiFi button for pretty much the same purpose:

https://www.stavros.io/posts/emergency-food-button/

A bit latent, but doesn't require a second press.

That's brilliant! I'd never have thought of designing my own hardware. Kudos

Me neither, but I gave it a shot and it turns out it's super super fun (it's now one of my favorite hobbies, I'm redesigning this right now: https://github.com/skorokithakis/esplights).

I definitely recommend it, KiCad is great, the people at #kicad are great, and the people at https://gitter.im/esp8266/Arduino have taught me most the little I know now. I can't urge you enough to try it.

BLE "tags"[1] cost ~$2 shipped and seem to send a notification every time their button is pressed. I'm not sure if they perform well in the case of powering down and then back up, though. It seems like they might need a button press to allow a host to reconnect to them, which would present the same problem as in the article. And they have awfully annoying beepers in them that beep with every button press, and beep multiple times before powering down.

1: https://github.com/sylvek/itracing2/issues/5

They will. For our smart socket the chips approach one dollar. Won't take long..