Arduino Uno for $2, NodeMCU for $3, RPi for $5... please let this trend continue. A year or two, and we'll basically have computronium - simple dev boards powerful and cheap enough to just tile your house with them. I've recently figured out that there's no point in designing your own PCB for placing sensors at home, when you can get an Arduino and an ESP8266 for $5; add power (and some ~$0 of voltage regulation) and…
Even more awesome: Skip the extra Arduino and use the ESP8266 as your Arduino. https://github.com/esp8266/Arduino
If I get an ESP8266, I can have something that run code, sit on my home network wirelessly and use it to do things like report on sensor inputs? Am I missing some larger expense that would be required as this seems very cheap compared to other options I've seen.