I think there is some confusion about those numbers.
The Great Smoky Mountain National Park amount was for land aquisition.
The Vietnam Memorial was for building, since the gov't already owned the land. Likewise the other Washington DC monuments mentioned were probably already government owned. Some were built on "reclaimed" land, meaning part of the Potomac or nearby wetlands were filled to create a building space (Jefferson, Roosevelt for sure & maybe the Lincoln).
If you don't include the 120+ years of building buildings, road, etc in Yellowstone, that park was "free". After the Black Hills were stolen from the native americans [Lakota Souix?] (in violation of previous treaties) the land was "free", so the cost mentioned was the cost to carve the sculpture.
Grand Escalante National Monument only involved the cost of the paperwork & studies & legal bills to move it from one classification to another. Unless you want to count the money not gained by the government from the various "extraction industries".
But the dollar amount for GSMNP is probably not for the roads, buildings, etc either. But do you work from a replacement cost model or the money spent less depreciation for deterioration of those roads?
You could do a lot of math and get an answer, but I'm not sure what question it would answer.