I disagree, on that with you, LordStark. Many times this has been done in other aspects of the game, eg. Missile Silo, I tried very hard to accumulate all that oil required to build it, only to see NEXON offering them 50% cheaper a week later. On the other hand, there could be some events that decrease citizens/time required temporarily (for example "all upgrades of Amelia require 1 citizen less and 10% less time to complete" for as long as the event is active (1 week))