Sales volume, market size, and market penetration also affect price. I don't have any hard sales numbers (so I am speculating a bit)...
Since Visual Studio is a product built for the US-market and then modified for international markets, its cost would be higher in foreign countries. The unit cost would be US_unit_cost + (localization_cost / anticipated_units_sold). In addition, the cost of internationalization would probably be added to all foreign units, but not the US units.
This is all before exchange rates. Then sales volumes will affect the per-unit cost of internationalization/localization.
Add to that simple economics--a product will sell for the highest price the market can bare. Is the competative landscape different in Europe? Does Microsoft perceive Europe to be a "growth" marketplace? Who are they competing with?