The Wall - Costly, Or A Bargain ???

It appears the cost of Trump's Wall might be $21.6 billion or more:

http://thehill.com/business-a-lobbying/318841-dhs-report-pegs-cost-of-border-wall-as-high-as-216-billion-report

But compare that to the cost of a single modern aircraft carrier - $26.8 billion:

http://www.facethefactsusa.org/facts/New-Aircraft-Carrier-Does-More-with-Less-Crew

And frankly, The Wall may indeed actually protect our country from invasion, while aircraft carriers are used mainly to kill defenseless people who would leave us alone if we were not bombing them from our aircraft carriers.

By the way, a modern version of Hadrian's Wall could be built for less than $1 billion:

http://www.thejournal.co.uk/news/north-east-news/company-looks-modern-day-cost-hadrians-4482251

And apparently that wall worked fairly well.