htc for swaps or sale ?

hi i would like to either sell or swap my htc one s for an iphone 4 am willing to swap phone and pay some cash if i phone 4 or s my phone comes in origional box have charger and usb cable . my phone is couple of months old would prefer swaps cos am after an i phone preferably on 02 as i have a contract on 02 many thanx for looking and hopefully a swap