I need sprint upgrade information?

Okay, so my phone has been eligible for an upgrade for over 1 year now, and I'm getting my upgrade. How much would it cost me to get an iPhone 4 or a galaxy s3?

Ok I have sprint and will upgrade June. Its 150 deduction, if you do ot over the phone they add it to your purchase, if you go in store they give you a rebate form to send that requires 30 days approval. Then they send you a rebate prepaid gift card. That you can use anywhere.