If shipping more durable items to the United Kingdom, Western Europe, and Australia, USPS Express Mail is hard to beat. Now you know about costs and the time considerations involved. Never, ever underdeclare a package. If he or she gets caught underdeclaring, you're an accessory, and the fines are stiff. Check to make sure you are not shipping something illegal.
Laws vary around the world.
Australia says no to prison art, currency, or certain philatelic items. Some Islamic nations consider 1950s bathing beauty art pornographic. And many countries will refuse even the most innocent item if packed in a box previously used to ship fruit, as there possibly could be microscopic pests inside. This sounds ludicrous, but don't ship anything that could be misconstrued as a bomb. I once mailed a box containing three children's novelty alarm clocks to a collector in Europe, and it was held up in customs for months because of the ticking.