For what it's worth, the West German government did honor East German marks 1-to-1, even though there was a gigantic disparity in value of both currencies. That alone was an enormous cost of the unification.
A lot of people thought that was a huge mistake. After the wall fell there was also a democratic East Germany for 2 years (?). I think a lot of people would have been OK with keeping them separate for a while but chancellor Kohl wanted to put his name on history and forced the reunification.