Fix for merchant price bugs

[cavedude]

To go along with the above post, there is a problem with this patch... It can happen that with faction/CHA modifiers, the price the merchant buys an item from a player can actually be HIGHER than they sell it for. A quick example, a player sells an item to a merchant for 300pp, the merchant then sells that item back to the player for 280pp, the player can buy/sell over and over making 20pp per each hand in. Of course, the player needs really high CHA and very good faction for this to work, but it is possible as it was done on TGC.