Trump's border wall has already cost the country $11 billion

The US Congressional Budget Office (CBO) has estimated that the 35-day government shutdown (from 22 December 2018 to 25 January 2019) cost the country $11 billion, $3 billion in December and $8 billion in January.

Now, I have no idea how that figure was calculated, but I have no reason to disbelieve the CBO, unbelievable though it may seem. So, Donald Trump's insistence on a border wall as part of a government funding agreement, which he knew would never be agreed to in these circumstances, and which he estimates will cost $5.7 billion (although other estimates put it as high as $285 billion!), has already cost the country $11 billion!

And it looks like he is willing to hold Congress hostage over immigration all over again. How's that Art of the Deal thing going?