Usually, it costs 1 civic per 100 units but now it has gone up to 100. This may be a bug.
edit, it recently moved up to 200 civics. Does the number of civics you have to pay rise the more you trade?
The civics costs are ridiculous on the gbt, I can't afford the cash price for stuff most the time and the civics on top of that just kills me. I normally only have around 15-25k civics and am always saving for research stuff.
My colony: https://www.my-colony.com/colonies/WDsSERFO/