Iphone 4 32GB Swap 4S 16GB *

Hi, I have a Iphone 4 32GB in black boxed and unlocked with charger, usb, earphones etc. Wanting to swap for a Iphone 4S 16GB preferably unlocked and in mint condition. Would swap for a 4S 64GB with some cash on top. Would sell for 300. Email with offers, Thanks.