ok i just noticed this....
dunno how it goes with other buildings, probably the same....
I have a stock market on a tile, I decide to change it to an industrial sector....
If I click on the stock market, select industrial sector in the right hand margin and click buy, it would cost me around 4300 to change it to an I.S
now then if I click 'upgrade' then click the tile again and click buy, it only costs 2500.
why is this?
is it a bug?
-taz