I haven't been able to sell my new PowerBook 1xx batteries internationally because nobody seems to want to deal with them on airplanes, even though I label the box and customs form that it isn't a lithium ion battery (it's nickel-metal hydride). I tried through USPS and they refused it at the border and sent it back.
Someone recently bought two on eBay through their International Shipping program where I only list them as shipping domestically and eBay has me ship to a local forwarder but they deal with repackaging it and shipping it internationally. Apparently they also failed because they just canceled this order but somehow I don't have to refund the buyer and eBay pays for it. I guess I don't get my batteries back though?