Connecting scattered devices to a central unit

I’ve recently been considering rolling my own home automation in my apartment lately, but I can’t seem to come up with a good way to control different devices scattered about from a central unit.

For example, let’s say I wanted to create a system to control my lights by creating little devices that used servos to flip my light switches. Nothing insanely complex. But if I wanted to control this all from a central location, we start running into trouble. I could do it wirelessly with ZigBee or Bluetooth or even Wi-fi, but I think that would quickly become prohibitively expensive.

What would be the best option to control all of these devices via a wired solution? USB cables that provide power and signal from the brains of the operation? 9V batteries powering each individual unit and 2 conductor copper cables to provide the signal? A powerful IR transmitter in each room that blasts a 3 bit identifier for each device to get it to change state (totally cool, totally infeasible)? What would you do?

Lowpowerlab.com

I like the idea Digitalstrom devices as it would be easy to integrate into the existing home wiring.

Not sure how difficult it would be to design your own system using the same concept.

www.digitalstrom.com/en/System/Overview/