Iphone 4s 64gb White on 02 and unlocked, 1 month old unneeded upgrade *

i am selling my iphone 4s 64gb, i am on 02 but i have had it unlocked by them. it is a little under 1 month old and not required as i still have my 32gb that i can use. i am looking for a decent offer near £500 as that is how much it sells for on auction sites. please contact me for further details phone will be restored prior to being sold. i live in bedlington about 10 miles north of newcastle, the phone will need to be collected from me and paid for by cash, happy to email photos if required. many thanks