Google has given its Chromecast Audio dongle a price cut in the US. The device, which usually carry a price tag of $35, is now available for $25 on the Google Store. Aside from Google's own Web store, Best Buy as well as the retailer's eBay store also has the device listed for $25, so you have some choice if you want to avail the deal. There's currently no information on when the deal ends, so you may have to act fast. Source 1 2 3
Source: http://www.gsmarena.com/chromecast_audio_currently_going_for_25_in_us-news-20700.php