Nest and Ecobee have a new challenger, the Amazon Smart Thermostat. [Amazon Smart Thermostat's appearance is quite simple: on the front of the thermostat, the temperature is displayed in large numbers, with up and down arrows below it. Between the arrows are small circles for changing modes.

The Amazon Smart Thermostat is currently available for pre-order on Amazon.com and will ship on November 4; the price without the C-Wire adapter is $59.99, rising to $74.99 if an adapter is required.

Amazon says that with rebates from power companies, the final price could be as low as $10.

Amazon's smart thermostat is essentially a square with rounded corners, more like an Ecobee thermostat than one made by Nest. Amazon states that it partnered with Resideo (Honeywell Home) to design this device. In fact, it resembles some of Honeywell's devices, namely inexpensive smart thermostats.

Measuring 3.6 x 3.6 x 0.8 inches, it is smaller than the Ecobee SmartThermostat but larger than the Nest Learning Thermostat.

Amazon's device is only available in white, giving it a clean look, but it may stand out if your walls are dark.

Like some other smart thermostats, the Amazon one works with Alexa, so you can create routines to change the temperature. Amazon's smart thermostat also relies on Alexa's instincts to automatically adjust the temperature when it determines you are home or away.

Unlike the Ecobee SmartThermostat, the Amazon Smart Thermostat does not have Alexa built in, so an Echo device is required if you want voice control.

Also, the Amazon thermostat does not support remote sensors, so it cannot adjust heating or cooling based on the temperature in a room other than the one in which the thermostat is installed. However, many of Amazon's new smart speakers have built-in thermometers, so it is likely only a matter of time before this feature becomes available.

Amazon's smart thermostat is not as smart as those made by Nest or Ecobee, but it seems smart enough for a device costing only $59.99. It is a bit surprising that Amazon has not integrated Alexa into the device itself and that it is only available in one color, but the low price is very attractive to those who want a smart thermostat but do not want to spend more than $200.

Will it make the list of best smart thermostats? Time will tell.