Unfortunately the reason the iSight (and I believe the Airport Extreme Base Station) are no longer available in Europe is because the products do not conform to the new RoHS (Reduction Of Hazardous Substances) regulations now in force within the European Union. Apple had two choices regarding its products - Change the product to conform, or stop selling it in the EU. For a few of its products it chose the latter option.
I'm quite sure we will see these products return to the store, but for now you'll have to look to Ebay.