(Disclaimer, I work for a sister company of Fibaro's UK reseller)
Depending on your definition of expensive you might like to look at Fibaro's z-wave switches. They're small wireless modules that go inside the switch box, sitting between the switch itself and the light circuit, allowing wireless control and monitoring of the switch. They effectively decouple the physical switch from the act of turning a light on and off.
You'll need a z-wave controller as well, and a bit of time to learn how it all fits together, but the flexibility it gives you is pretty impressive.
From what I've seen of them, no - they effectively turn the single loop between switch and powered device into two distinct things, the switch(es), and a relay that can turn the device on and off. Even if they could be it would involve opening up the switch/socket box and removing it to get at the actual device, which you'd presumably want to kill the entire circuit for anyway.
Depending on your definition of expensive you might like to look at Fibaro's z-wave switches. They're small wireless modules that go inside the switch box, sitting between the switch itself and the light circuit, allowing wireless control and monitoring of the switch. They effectively decouple the physical switch from the act of turning a light on and off.
You'll need a z-wave controller as well, and a bit of time to learn how it all fits together, but the flexibility it gives you is pretty impressive.