Given that Xbox LIVE Gold Membership is often a tenner more than this, we suggest you snap this one up sharpish. Also, remember that Xbox LIVE Gold Membership will carry over to the Xbox One.
NB. Please note, you're paying for a digital code, not a boxed card. SimplyCDKeys is part of SimplyGames, who we've used many times before without issue.
Cracking spot, crimpshrine!