WANTED - Samsung Galaxy S3 £300 cash paid no messing around !

Wanted Samsung Galaxy S3. Must be in good condition with box and accessories, white or blue.. Needs to be unlocked preferably but if not can be on either 3 Network or O2. Will pay 300 cash and not mess you around, I am not interested in buying a stolen phone though so you must have proof of purchase, a receipt or delivery note etc. I can collect from most areas in London.