Not quite the lowest price for this kit, but close. This kit with two 3-way smart light switches can be used to add automation to those 3-way light setups that many homes have. I believe that you can use just a single switch in conjunction with an ordinary 3-way switch and get essentially the same results, so this kit can be used for 2 different circuits, but I could be wrong so do your own research.

Amazon product: Kasa Smart WiFi Light Switch, 3-Way Kit by TP-Link, Works with Alexa Echo & Google Assistant (HS210 KIT)
Customer Reviews:
I waited what felt like an eternity for the 3-ways to arrive in Canada. The units were just delivered today and, so far, they haven’t disappointed. Once setup they work the same as the 2-ways in terms of how they appear in the app and connected to Google Home. | There was a wonderful review on the Amazon US site pointing out that you don’t need a unit on both ends of a 3-way circuit. I can also confirm that one unit will do, which means that you can use the 2 pack to smart-ify two different 3-way circuits. | Very pleased with the purchase.