You have mastered one aspect of bartering - the ability to buy goods far cheaper than a normal person. With this Perk, you get a 25% discount when purchasing items from a store or another trader.”— Fallout description
Adds a -25% discount to purchased items. The actual discount varies between 15 and 30%, as the game appears to apply the cumulatively, rather than sequentially. The Fallout 2 manual incorrectly states that this perk makes the player's own items more valuable, and that the Barter requirement is 60%.
Either way, the perk is functionally useless, as there is no shortage of money in the games, and the original Fallout barter system made it easy to make a profit early game with moderate barter skill.