Chromecasts are basically required accessories for TVs at this point, and Google Home is a solid alternative to the more-expensive Amazon Echo, so when you can save $40 by buying both together, you should jump at the chance.
The deal is technically $15 off when you buy any Chromecast (including the 4K Chromecast Ultra) and a Google Home together, but Best Buy’s taking an extra $25 off any $100 order when you use Visa Checkout, bringing your total savings to $40. Considering the standard Chromecast is priced at $30, that’s like getting it for free, plus a $10 discount on the Home.