Instore only on O2 the brand new Cybershot C902.
Tell the salesperson that you have O2 PAYG already and tell them any O2 PAYG number that has been in use for 14 days or more (doesn't have to be your number, friend or family etc will do. You get the unlocked sim-free C902 without needing to buy top up etc. You can save an extra £10 by trading in an old phone and charger.
This saves £50 off the sim free price for exactly the same box/phone off the shelf.
Currently the only place selling the C902 on PAYG if I am correct.