You dont pay less money to repaira broken item to a slightly less broken state, the upkeep there is based on the purchase price of the original item. You cannot buy heirloomed items, yet you pay a significantly higher upkeep for the same item. It destroys the reason for heirlooming if you pay the same price as a more expensive equipment piece (say armor) with not enough of an increased benefit (+2 body armor) to compensate for the higher upkeep. Youa re better off using the higher end armor unheirloomed, then using lower end equipment that has been heirloomed. The heirloomed item's upkeep should be based on the purchase price of the original item just as the original items's repair rate even when broken is based on its original price.