Google is offering a sweet deal for those who purchase a new Chromecast or Chromecast Audio: they will give you $10 in Google Play credit following your purchase. That's right, purchasing a new Chromecast from the Google Store nets you $10 to buy apps, games, movies and more from Google Play. Google doesn't specify whether the promotion is only valid on Chromecasts purchased directly from its store or if other retailers are included, but based upon previous promotions we expect that it is only through Google.
You need to make your purchase between February 3, 2016 and February 24, 2016 in order to qualify for this promotion. The credit will need to be applied to your account by the end of May, and it will expire at the end of December.
Source: Google Store (Twitter)