Upgrading Magic Items Cost

[Sentack]

The rules for upgrading magic weapons and armor aren't that bad, you go with the cost of the difference between the two current item state to the state you want to upgrade it to. The only question is, is this the cost for a 3rd party to upgrade the item? Can a player upgrade an item if they have the specific magic item feat for cheaper?

Quick example:

Bob the Fighter has a +1 Frost Longsword. Bob wants to upgrade the weapon to a +2 Frost Longsword. The cost of a +1 Frost Longsword is 8k gold. The +2 Frost Longsword is 18k gold. Cost difference equals 10k gold.

But along with Bob is Steve the Wizard. Steve knows the "Create Magic Weapons and Armor" feat. If Steve was making the item from scratch, he would get 50% off that value. So if Steve were to upgrade the magic item himself, would cost be 5k gold instead of the full 10k?

It seems logical but I don't see any clear examples where this plays out and I wanted to check in here first.

[Malfus]

You are correct

[LazarX]

The eaiset way to do this is the following.

1. Decide how the item is going to be upgraded.

2. Construct the item to be upgraded as if it was going to be designed from scratch.

3. Construct the item as it is already as if it was being built by the same method as 2.

4. Subtract 3 from 2. That's your cost.

[Sentack]

Taking half of the difference actually equals up to exactly the same value, so that's what I can use for now.

But in general, I'm glad this is correct. Now I just need to land in a windfall of a few thousand gold and I can maybe.. possibiliy... in a remote chance.. upgrade some of my party's gear.