on the google store, they're giving £10 off the chromecast selection (audio and the normal chromecast)
Originally £30, now £20. Offer valid from 21 November 2016 from 12:00 a.m. Pacific Standard Time to 5 December 2016 ending 11:59 p.m. Pacific Standard Time. This offer cannot be combined with other offers or discounts. Offer is non-transferable and not valid for cash or cash equivalent. Offer is for UK residents only. Void where prohibited
edit: +FREE DELIV.