iphone 4 32gb or swap for S3 and cash on top +

I have a iphone 4 32gb was replaced by apple abt 7 months ago. excellent conditon always in case and screen protector,On o2 hardly a scratch. Has box, usb and charger, and also i have a Gevy pro sim adaptor to unlock to use on most networks. would consider swap and cash on top for a samsung S3.