Yes I agree I have myself mentioned this !

bonnieslayer FT said:

I just checked to see about upgrading my gates then seen they cost 42000 sapphires to do. It would be cheaper by far to destroy then rebuild them so is this a bug or are they supposed to be outrageous to upgrade  ?

http://prntscr.com/p4uzd4

Hello,

Thanks for your report. Please note that this is not a bug. The difference comes because of defensive buildings that may be located on top of the Gate. The price goes up since, for example, your Catapults can be saved, but not destroyed once there's no more free space.

Nevertheless, you may leave your feedback in the appropriate Forum category.