Sensi Wi-Fi Thermostat | $93 | Amazon

To be sure, the Sensi Wi-Fi thermostat isn’t as sexy looking as a Nest or Ecobee, but it has the same basic feature set for under $100. You can control it via a smartphone app, Apple HomeKit, or even Alexa, so we’re willing to overlook its decidedly average industrial design, especially since today’s price is an all-time low.