I am eligible for an upgrade and currently have the Iphone 5C. As I was told my 5C is worth $200 trade-in. Therefore, I want to put that $200 towards the 199.99 fee for the Iphone 6s and only pay the $40 upgrade fee. What is my best way going about this? to wait until it comes into stores and trade my phone in and get the 6s or to preorder?