white i phone 4 16gb locked to o2 .

i have a white i phone 4 for sale. its 16gb, and locked to o2 but im sure it can be unlocked. its in really good condition as it has had a screen protector and case on it (which i will include). it comes complete and boxed. selling due to upgrading to the i phone 4s. am asking for £300 but will listen to offers. i can post but to uk addresses only (if you cant collect from kent)!! no time wasters or scammers please. im not stupid. any qestions please ask.