Especially in consumer electronics, a large number of goods are offered only in some countries. Usually this holds only for products which have some close substitutes available (e.g., screens, where a particularly cheap models are often only sold in the U.S. but not in Europe). Such cases are not too hard to explain via price discrimination.
However, I recently found out that there exist products which do not have close substitutes such as Sony's E-Ink readers but are nonetheless only available in some countries. (Production limitations were my first thought, but the example product is already several years old.) Given that the online retailer market is very efficient and that consumer electronics have large development costs I could not come up with a reason why consumer electronics producers would willingly restrict their own market size.
Since I do not believe that producers make such decisions without good reasons, I would like to know what these reasons are. Note that the example product is not the only case, similar cases can be found earlier in the cell phone and PC markets.