Google’s fourth-generation Nest Learning Thermostat (the latest model) is one of the few smart home accessories I rely on every day, and it’s at an all-time low price of $218.99 ($61 off) at Amazon for Prime Day. Prime Day is almost over, but Best Buy and Google are also offering a $40 discount. Previous versions of the Google Nest Learning Thermostat required a C-wire to provide power, but that’s no longer the case. However, we still recommend using Google’s compatibility checker to be 100 percent sure it will work with your HVAC system. The fourth-generation Nest Learning Thermostat is one of the few gadgets besides my smartphone that I rely on daily, and the only smart home accessory I consider a necessity.