Switchbot, the robot button pusher, Has a prime day coupon at 30% off on both the hub (which you will need to get IFTTT, which is how you do smartthings integration). So that brings the price of the button down to about $20 and the price of the hub down to $34. Buttons come in black or white.
There’s a glitch in the coupon and it will only apply to one button in an order. So if you want more than one button, you have to place a separate order for each one in order to get the coupon discount. You could order the hub and one button in a single order and get the coupon discount on each. So just check the subtotal before you check out to make sure you got the coupon discounts you expected.
I just posted a review of the 2019 version of the SwitchBot in the following thread:
2019 Switchbot Review ( robot button pusher), integration through IFTTT
And the Amazon offer: