def price_get(type)
      supply = find_or_create_supply_detail
      if type.nil?
        supply.prices.first
      else
        supply.prices.find { |p| p.price_type_code == type }
      end
    end
def price_get(type)
      supply = find_or_create_supply_detail
      if type.nil?
        supply.prices.first
      else
        supply.prices.find { |p| p.price_type_code == type }
      end
    end
retrieve the value of a particular price