Every building is different, the way to figure it out from an appraiser stand point is this:
Find an IDENTICAL unit on a different floor and calculate the difference in price between the two.
There are many factors that would affect this though: The unit needs to have sold at the same time, similar condition, view, etc...., if it hasn't you would need to calculate how much it has increased or decreased since that time of sale.
It is very difficult to usually find an identical sale that sold similar to the one you are looking at, if you need help with this. Send me info on the building and I would gladly look into it for you.
This is not something that has a set dollar amount on, if anyone tells you that.... they are wrong.