Best Buy offers the Google Chromecast Streamer for $29.99 with free shipping. When you add it to your cart, Best Buy adds a $20 Google Play credit. Additionally, once you get your Chromecast, you will also get another $20 Google Play credit along with 3 months of free All access Music from Google as well as 2 months of Free Hulu Plus for new users by connecting here.
You also get 3 months free of Drama Fever and a free original X-Men movie.
Update: Addressing comments below, you get a $20 Google Play discount emailled to you after purchase. (see graphic below). Then when you activate your Chromecast you get ANOTHER $20 Google Play credit (As long as it is your first Chromecast).