Samsung Galaxy S2 Plus Cash for iPhone 4/4s -

I am looking to trade my Galaxy s2 for an iphone 4/4s. Galaxy s2 is boxed and locked to o2/tesco i can unlock if needed. I am willing to pay cash on top of my phone but that depends on which iPhone you are offerring. Please text me with what you have and how much you would like on top and if i like what i receive i will call you back. NEED ONE ASAP Thanks