Blacksmithing System Costs Explanation for Nerds

There's a basic summary of how the costs for the new (as of October 2023) blacksmithing system are calculated in-game, but I wanted to provide a more detailed explanation and some notes here, for those who are interested.

First, the script checks if you're under the item value limit. In general, +7 items can't be improved further, but you can do quite a bit to a +5 item. Assuming you're under the limit,

((BaseCost*ItemPremium)*RepeatPremium)*DiscountFactor = FinalCost

The Base Cost is determined by the type of material and the type of item it's being applied to. I won't list them all here, but in general they're roughly based on the cost of buying an item with the property being added from a shop, minus a bit to account for effort and material costs. For example, if Silveri sold a +5 Longsword, it would cost around 300k. The base price of using an Adamantine Bar to make a weapon +5 is 250k, a discount of 50k. There are exceptions where the smithing base cost is somewhat higher for one reason or another but this holds in most cases.

The ItemPremium is a multiplier based on the current GP value of an item, prior to the smithing. Again, the exact details of how this is calculated don't need to be shared, but the point is, the more valuable an item is, the more it costs to smith. The first 10,000GP of item value are ignored, so items worth 10,000 or less have this as a 1x multiplier, after which it starts increasing. There is no limit to this multiplier, so high value items can become extremely expensive to improve further. This is intended.

The RepeatPremium is a multiplier based on how many times the item has been smithed in the past. This is a 25% price increase per smithing. E.g., the multiplier is 1.0, 1.25, 1.5, 1.75, 2.0, etc. etc.

It should be noted that the RepeatPremium is only applied when adding a new property. So for example, if an item has been smithed 3 times already and has no enhancement bonus, adding an Adamantine Bar to it in order to make it +5 will attract a RepeatPremium of 3.75x, potentially making it incredibly expensive. However, if the item already has an Enhancement Bonus of at least +1, the RepeatPremium will be skipped. The tracker of previous smithings will still increase by 1, however.

Finally, the discount factor is applied. This depends on the material being applied, but I have tried to be fairly generous. For example, when adding Adamantine to a weapon, the discount is simply 20% per current level of enhancement. E.g., +4 gets and 80% discount, +3 60%, etc. You also get a discount if the weapon already has an Attack Bonus, but it's half the size. E.g., +4 gets a 40% discount. Similarly, if you add Iron Spikes to a Piercing/Slashing Type weapon, you get a 50% discount because the Extra Melee Damage Type: Piercing property is not needed on these weapons.

A couple of notes on minimising your costs:

Doing more expensive smithing jobs before cheaper ones is usually cheaper overall. Adamantine adding +5 to a weapon has a base cost of 250,000. If you have a high multiplier from item value due to other properties and many repeat smithings, this can get very very expensive.

Thanks to the generous nature of the discount calculation and the way the base prices are set up, it is slightly cheaper to do, for example, Steel to reach +3, and then Adamantine to reach +5, than it is to just do Adamantine directly. The downside to this is that it increase the number of times a weapon has been smithed more than just going to adamantine directly. Whether or not that matters depends on how much more smithing you plan to do with that item.