As the title; I have had the window pop up for me a couple times as a turn notification "you have the influence dosh to do this" but I honestly have no idea where in the UI the button that allows me to open it whenever I want (say, to see costs) is lurking? Anybody find it?

On the top right there are 2 buttons.  One is for units and one is for cities.  Click the city one and there is another button inside that menu at the top that opens the wonders screen.

Thank you very much! Also I guess the pop up didn't come because the jerks took em already. :|