Cheapest i can find currently £42.95 on amazon.
The Game Control Mount GCM10 is designed to accommodate DUALSHOCK®4 wireless controller by Sony and a smartphone or tablet with screen size 4” – 8”
Officially supported devices here
Sony Z3 Compact
Sony Z3 Compact Tablet
Unofficial support for android phones and tablet herehttp://forum.xda-developers.com/android/apps-games/ps4-remote-play-t2929147
Jailbroken ios support here
Jailbroken iOS device with the 'Controllers4all' app installed.
NOTE PS4 CONTROLLER NOT INC.
Product Info from sonyhttp://www.sonymobile.com/gb/products/accessories/game-control-mount-gcm10/
Bring your favourite games and controls anywhere in your home. Immerse yourself, and win big. With your Remote Play games online, you are free to go anywhere. Authentic With its dual analogue sticks and trigger buttons, shock vibration and touch pad, your DS4 wireless controller is as good as ever! Experience better knowing you can play your best anywhere! Free Play from anywhere on your home Wi-Fi network. Game Control Mount GCM10 will securely hold your DS4 and Smartphone where ever you are! Freedom is the best feature. Compatible Game Control Mount GCM10 is designed to accommodate DUALSHOCK®4 wireless controller by Sony and a Smartphone or tablet with screen size 4 - 8 inches
£18...still cheaper than RRP though also worth noting, Code doesn't work on this item. (I'm a new customer also)