Board Thread:News and Announcements/@comment-5089372-20130419121530/@comment-7486518-20130428045724

That's normal cost for Expansions (speeding up)

As far as I know it's always been 10 gold per hour... It has since I started playing, and it's stated it on the Expansion page for a while before that I think (Honey started playing first)

But it may have been different before that... But as far as I can see it hasn't changed in the recent past =)