Some Walmart stores ares selling the 2nd generation Chromecast (Model: NC2-6A5) for only $9. Availability varies, but you can check Brickseek to see if its available at stores near you.
Even if there’s none close by, you can try your luck with Best Buy over chat and ask them to price match. There’s plenty of positive data points on SD. You can use this link to show them the Walmart price.
Pretty good deal, as these usually cost about $30. You can even buy a few. Could be a nice Christmas gift as well.
Let me know if you find them near you, or if you have any luck price matching.