For what it's worth, I really recommend Stripe. It took me about two hours to write my home-built store using it, and I plan on using it on a new project soon.
I'm already signed up to be notified when it becomes available to use in Europe. Until it does, FastSpring certainly seems good enough (and defers the effort of setting up a non-static website to handle purchases, which is worth a fair bit to me as well).