Emerson Thermostats via Rakuten offers the Emerson Sensi Smart WiFi Digital Thermostat for $129. Coupon code "HOME20" cuts that to $103.20. With free shipping, that's the lowest price we could find by $5, although it was $24 less in December. This thermostat is compatible with Amazon Alexa, Apple HomeKit (c-wire required), Wink, and Google Assistant. It allows for WiFi control via Emerson's iOS or Android app. Two AA batteries are included.
With these companies, it might be easier than you think to negotiate your monthly bill down.