Only 10% off, but the Sunbeam WiFi mattress pad is now in stock lots of places, including Amazon. $113 with discount for the queen size. Integration with ST through Alexa routines. Voice control via Alexa or Google. Some people report the blanket version is cheapest at Walmart.
We’ve had ours for about a month and really like it. Unlike earlier models from other brands this one WILL let you preheat remotely, although if you set the heat above level 4 (of 10), it will turn itself off after 60 minutes if you don’t confirm by pressing the physical controller. But you can also put it on a schedule. So fully handsfree control and you can turn it on and off from ST by using Alexa routines as an intermediary. 
As I noted in the discussion thread, the queen and king size have two zones you can control independently with the app or the physical controller, but Alexa treats it as one zone. Didn’t matter to us, but it will to some people.
Just crawled into bed and it is freezing.... how do I change that? - #25 by JDRoberts