Haggle

Haggle (Cha)
If you dream of riches, haggle will be your best friend, allowing you to buy and sell for much better prices.

The basic formulas are:

Selling: Base percentage + (.25% * Haggle)

Buying: [1 - (.005 * Haggle)] * Markup (Markup varies depending on Vendor/level of Broker)

Table progression table
Here is how haggle impacts the buying and selling price of items, at the different vendors.