If you ever pay for software in Euros, always
switch the basket to US dollars first and compare the amounts. Most of the time the payment processor converts between dollars and Euros using whatever exchange rate is current. Since they often add a surcharge for currency conversion, occasionally you may be beter off paying in EUR if the company is located in the EU.
But sometimes they don't bother to do any conversion at all - and you may see this:
Basket with price in Euros:
Basket with price in US dollars:
At the current rates, the difference is nearly 25%.
(And I'm still not buying this upgrade, I don't think. A worthwhile object lesson though.)