Your intrinsic knowledge of objects’ value, combined with your shrewd people skills, allow you to get substantial discounts.
Benefit: Whenever you purchase an item, you may make a special Diplomacy check, with the DC equal to 20 + the merchant’s Charisma modifier (between 20 and 22 for most merchants). For every 5 ranks in Appraise you possess, you gain a +1 bonus on this roll. If the Diplomacy check is a success, you purchase the item at a 10% discount. For every 10 points by which you exceed the check’s DC, this discount increases by 5% (to a maximum of a 20% discount). If you fail the DC by 4 or less, the price of the item is unchanged. If you fail the DC by 5 or more, the merchant actually increases the price of the item by 10%.