Please make it use standards or at least don't directly use Google's or Office APIs. It'll be way easier to support a lot of calendars (including Google Calenda

Please make it use standards or at least don't directly use Google's or Office APIs. It'll be way easier to support a lot of calendars (including Google Calendar) if you stay with CalDav in mind than the other way. However, I like the idea. That said, 199€ is not cheap. It will be really hard to sell at that price.