code: def price_set(type, num)
        p = price_get(type)
  
        # create a new isbn record if we need to
        if p.nil?
          supply = find_or_create_supply_detail
          p = ONIX::Price.new
          p.price_type_code = type
          supply.prices << p
        end
  
        # store the new value
        p.price_amount = num
      end
docs: set the value of a particular price