Well... the really cheap ones are just timers/thermometers. The amount of control you have over it is related to how much you can program it. I used to have one that was very simple: I could set 2 times/temps for the week and 2 for the weekend. It was easy to program but didn't have much smarts. SO on days that I worked form home, it still let it get hotter/colder for my pre-programmed "away" time frame. So I was constantly tweaking it when I was not really away. My new house had some fancier ones that gave me more times/temps to program and I think I could adjust them per day (not just "week" and "weekend") but it was actually overly complicated to program. And some of the fancier ones still cost $150-175 at HD. So at $250, the Nest is not that much more expensive than some of the fancier ones at HD. But you get some much more "smarts" with it. And you get all the cool extra stuff like remote access, monthly usage reports, habit learning, etc.