Since the prices for the clamshell iBooks, especially for the 300MHZ models in Tangerine and Blueberry, are much lower in the US, it is worth checking out the eBay listings there, provided you can pay with PayPal, which most US sellers accept.
If the seller only wants to ship to PayPal customers with a verified address, you must ask before the end of the auction whether you can bid, since serveral German PayPal customers cannot have their address verified.
Two disadvantages of devices from the USA are that they have an international keyboard without German umlauts and that you have to buy a suitable power cable for around 6 euros here in Germany. The YoYo power supply also runs with the 220V that is usual in Germany.
Cheap shipping via USPS
Before the end of the auction, ask the seller whether shipping via the United States Postal Service (USPS) is possible, because shipping via UPS costs many times over. USPS offers several shipping options. The cheapest option for a 10lb (5KG) package is Priority Mail Flat Rate Box, takes 6-10 days. Shipment tracking is possible.