Well... that does change things a bit I guess...
Looking around I am finding that around $15 million for legal fees and etc. will come from the National Endowment for the Arts (NEA) and this is normal for monuments and memorials in DC. The arch requires Congressional approval and this also involves the NEA which performs oversight.
The $100 million for the arch itself will come from private donations. My family will definitely kick in to support this.
Some in the media are trying to portray the $15m NEA cost as the price of the arch itself which is not true.