Hello everybody, I own a galaxy s3 and i would like to take it to T-mobile and get it traded for an s4 and a topping of my own cash. The phone is still on a contract from 9 months ago. It has dings on the bezel and a scratched back and a couple scratches on the screen. I'm giving the condition information because t-mobile credits you based on the condition of the phone. Please tell me how much I would have to pay extra to get the s4.