It isn't as easy to ship merchandise overseas as it is a letter because you may be required to have a lot of extra dumentation, permits, etc. I would think twice before I ordered from a small business overseas, especially if they don't have a demonstrated knowledge of shipping items into the US.
Both the buyer and seller should have a mutual understanding on how the item is going to be shipped, if customs duty is due, on the required paperwork that must accompany the items for export and import, etc. Without all this all involved are asking for trouble.
If it is merchandise you may have to pay a customs duty on it. If paperwork is not complete, you could be hung up in customs indefinitely.
To minimize costs, inexperienced buyers and sellers may decide that surface shipping is the way to go, but it can take months. UPS, FEDEX, and other services will do it much quicker but at a cost. It's probably more than the cost of the items, especially if you have to pay duty on the items. On the plus side, you can have these companies act as your customs agent to expedite your shipment, but again, it is expensive, but at least you'll have a tracking number and paper trail.