I agree their pricing is confusing for non studio related usage, I've just sent them an email asking to clarify.
At least the german voice from Google is IMHO as good as the voice from Ivona (in fact it's even more applicable as it sounds more formal while the Ivona female voice might have a slightly Berlin accent or so).I'm not a German speaker so I can't comment on the accent - but I'd have to disagree about the quality from Google on the German voice sounding as good as the Ivona one.. there is clear choppyness on the Google voice, where as the Ivona one sounds more clean.