How much will an upgrade cost?

I have a really old iPhone (iPhone 3) and it's been over a year (I believe 2 years) since I've had it and I'm eligible for an upgrade. I want to upgrade to an iPhone 5s and I'm wondering how much upgrading to an iPhone 5s (16GB) would cost me. My phone carrier is AT&T.

Verizon right now has 5S for $99, started yesterday.

  • How much would the iPhone 5 cost with an upgrade from Verizon? I'm getting an upgrade in December and I know the 16 GB iPhone is $199, but wouldn't it be cheaper with an upgrade? I would just need an estimation.
  • How much would it cost to upgrade to an iPhone 5 on Sprint? I JUST got the iPhone 4 a few days ago (sunday and today is thursday). But, the iPhone 5 has just been released for preorder.So, how much would it cost to trade in the phone for the 5 (by the way, when i got the 4, it was on a new 2year contract).
  • How much would it cost to upgrade my iPhone? I currently have an iPhone 3GS from at&t. I have had my contract since december of 2011, and I'm pretty sure the contract ends December of 2013. I want to upgrade my 3GS to an iPhone 5 when it releases, but was wondering how much that would cost(estimation). Do you think there would be some type of deal on the iPhone 5 for people who want to upgrade? I've never upgraded a phone before so I don't know how this works.
  • How much would it cost to upgrade early with Verizon? My cousins just got a new phone so she gave me her iPhone 4. How much would it cost to upgrade early?