Vendor prices, bartering and attitude formulae + tips for buying and selling

I did a little bit of testing on attitude, bartering and charisma and here's what I found:

Vendor prices are affected by attitude and bartering skill.

First off, attitude seems to simply be (charisma+reputation)*5. Attitude is capped at 100, and I'm guessing bartering is functionally capped at 5, otherwise with high attitude/bartering you can eventually buy items for less than their worth and resell them for more.

Items have an actual value listed on the tooltip, but you usually pay a hefty markup. For buying items you start off paying 2.5x the actual price at 0 attitude and 0 bartering. The full formula for the price increase factor when buying is:

-0.005*Attitude+2.5-(Barteringskill/5)

I focused mainly on the formula for buying, however the one for selling is similar to the buying formula but starts at 2.5x less (0.4 factor) at 0 attitude and 0 bartering. So you can just use:

1/(-0.005*Attitude+2.5-(Barteringskill/5))

Anyway, what this all means is that with:

• 0 attitude and 0 bartering, you pay 250% and sell items for 40%

• 100 attitude and 0 bartering, you pay 200% and sell for 50%

• 0 attitude and 5 bartering, you pay 150% and sell for 66.7%

• 100 attitude and 5 bartering, you pay 100% and sell for 100%

Note: This was all done with limited testing, so I could be mistaken somewhere, but the formula matches what I'm seeing in-game.

General tips for buying and selling:

• You can keep items with +bartering and +charisma and equip them before talking to a vendor (if you can be bothered). You can craft +1 charisma belts, rings, and amulets. See the crafting guide for more info.

• You need to approach the vendor with your character with the highest attitude/bartering skill, however once in the trade screen you can switch between characters and keep benefitting from the extra discount. On the other hand, if you approach with a character with a low attitude/bartering skill and switch to your smooth talking politician character inside the trade screen, you won't have the extra discount.

• Keep in mind that henchmen and companions have no charisma stat and probably have less reputation than your main characters.

• Some quests reward extra attitude points towards an npc, so do your shopping/selling with them if possible.

• You can give NPCs money and items and you will get (partywide) attitude in return. 20 value or gold equates to +1 attitude (200 gold for 1 attitude for Teller of Secrets). Meaning 2000 gold raises their rep from 0 to 100. It might be worth it if you do a lot of trading with an npc, but the generally low amounts of gold they have available probably makes it not worthwhile. Keep in mind reputation is free attitude!