I have iPhone 4S 16GB Black and want to sell it so i can get iphone 5.I tried to sell it to my cousin for $400 but he offered me $350 and showed me this latest price report for confirmation http://www.movaluate.com/apple/iphone-4s-16gb-att-black I want to ask should i believe in this and sell my iPhone 4S for $350 or can i get more for my device ?