anchor.diff:  
         (let ((cost (vendor-get-value obj
                                       (markdown-of shop)
  -                                    (cost-modifier-of ch self)
  +                                    (- (cost-modifier-of ch self))
                                       (currency-of shop))))
           (perform-say-to self ch (format nil "I'll give you ~d ~a for it!"
                                           cost
  
positive.code:     ;; Other item flag modifiers
      (when (is-obj-stat2 obj +item2-reinforced+)
        (incf percent 25))
      (when (is-obj-stat2 obj +item2-reinforced+)
        (incf percent 25))
  
      (incf percent modifier)
  
negative.code: 
          (let ((cost (vendor-get-value obj
                                        (markdown-of shop)
                                        (- (cost-modifier-of ch self))
                                        (currency-of shop)))
                (amt-carried (if (eql (currency-of shop) 'gold) (gold-of self) (cash-of self))))
  
  