Amazon offers Prime members the Lifx Edison Multicolor A19 75-watt Equivalent WiFi LED Smart Bulb, model no. LBA19E26UC10, for $39.99 with free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $6.85.) That's the lowest price we could find by $20, outside of the mention below. It features built-in WiFi, which allows you to remotely control the bulb's settings (such as brightness level and color), and it works with Alexa for voice control.

Update: It's now out of stock at Amazon; however, Best Buy has it for $39.99 plus in-store pickup.