Comment Check out Ubiquiti Networks (Score 1) 189
I use the Ubiquiti mFi mPower to control a lamp remotely. That's a very basic setup for this system, but it has been very reliable compared to other solutions I've used. There's an iPhone and Android app, and you run the server on a local machine, so there's no third party to go through. They also offer various sensors, such as a temperature sensor. I'm not sure if it's cheap enough, but otherwise I think it might meet your needs. www.ubnt.com