A motion/temperature sensor from Monoprice: $30.
A VeraLite-G (eBay make an offer): $135.
A Z-Wave thermostat (2-gig CT100 that can display humidity on the main display): $80 (I got a couple for $62 on sale)
No dependency on Google to control your home: priceless.
Disclosure: I use MasterCard sometimes.