Looking to swap an iphone 4 black for a white version +

Looking to swap an iphone 4 black (factory unlocked) for an iphone 4 white My iphone has no marks apart from a couple small ones around the dock connector. Always had a case on and unlocked. Or Swap my iphone 4 black (sim free) and galaxy s2 (locked to 02) for an iphone 4s white/black, please message me Please email me, i have cash aswell for part exchange