I would definitely use a scale to get an idea before hand what to charge. If it is heavier item consider shipping via Fed Ex. And like previous posters mentioned printing shipping labels through ebay is cheaper, ebay offers a discount. Sometimes its not that much but sometimes i am happily surprised. I always use a flat rate shipping and figure the law of averages for me usually works in my favor, but many times i cringe when the zip code is west coast. I pay the shipping and move on and do not dwell on it because usually everything i sell is found money.