Does radio shack charge to trade?

I have a sprint lock iPhone 5s but I want to trade for a space grey t-mobile 5s would they charge more?

You will get only cash credit for your used sprint iphone 5s. It will be no where near what the value of a new T-Mobile 5s is.

There's no profit in a straight swap and that's what they're in business for.

Even if your phone was brand new, boxed and unused they would still be looking to pay you rather less than they buy them direct from Apple for.

You'll get far more by selling yours privately and then using the funds raised towards the model you want.