Commerce

has a bartering system where items vary in price based on a multitude of factors. Commerce is the base value that is specified for each item that is then multiplied or divided by a multiplier depending on selling or buying.

Trading Multiplier Formula
If the player has Glotrot, Ego modifier and Snake oiler no longer have an effect and returns a flat -3. The equation then becomes

The multiplier cannot be higher than 0.95(achievable with +9 Ego modifier or +7 Ego modifier with Snake Oiler) and the multiplier cannot be lower than .05 (-5 Ego modifier).

When buying an item from a trader, this multiplier is divided by the value of the item in question. When the item is sold, the value is multiplied by the multiplier.

Reputation Effect on Trade Prices
Reputation with the merchant also affects trade prices, acting essentially as a bonus or penalty to the player's ego modifier.

Sacred Well Reputation Formula
How much reputation the Sacred well gives is also dependent on the commerce value of the object.

$$ \text{Reputation} = \text{Commerce}/10$$

Reputation cannot go lower than 1, and if an object that has no specified value defaults to 10 reputation.

Book Experience Formula
$$\text{Exp} = \text{Floor}(\frac{Commerce^2}{25})$$

Modifications and Commerce
Each modification has a Value attribute that is multiplied against the base Commerce value to get the new modified value.

Items by Commerce Value
Note for liquids, their base commerce is multiplied by 4 to have an integer weight.