Sensi Wi-Fi Thermostat | $95 | 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 the best Amazon’s listed in several months.