Anyone who has worked on a large scale construction project from the economics side of things, will tell you it is common for them to run over budget and behind schedule. A construction project on the scale of the proposed border wall (or fence, or whatever he's calling it today) isn't large, it's staggeringly massive. Keep in mind that there already exists a towering Mexico-U.S. border barrier, and that it was built over the course of many years, and continues to be maintained and upgraded.
Estimates from many experts familiar with large scale construction projects --including projects funded by the government-- say a realistic estimate for what it would cost to build a wall (even a modest one) along the Mexico-U.S. border would be around $20 - $25 billion; far more than the $5 - $5.7 billion number thrown around by Donald Trump. Even analysts from the propaganda wing of the White House, Fox News, agree on that estimate.
So how over budget could a wall of this size in 2019 or 2020, cost? When it was first proposed by then Vice Premier Zou Jiahua, the Three Gorges Dam in China (which began construction in 1994 and completed in 2003) was said to cost $8.35 billion.
It ended costing $37.23 billion in the end.
So a wall --that would require us to cover nearly two thousand miles of border that must straddle over desert, mountains, rivers, privately owned land, natural wildlife habitats, as well as having to transport materials, machinery and workers, build access roads and construction sites, AND require thousands of workers working hundreds of hours in tough conditions-- would definitely end up costing us far more than $5.7 billion. The U.S. would actually save money by throwing that money into a bonfire instead of attempting such a wasteful use of tax dollars.
Look I get it. I love Lord of The Rings. I've seen the Great Wall of China (or rather, what's left of it): Big imposing walls are cool. The biggest, strongest, longest walls can stop anything and everything...Except planes. And tunnels. And well built ladders.
On second thought, Donald, if I can beat your $5.7 - $25 billion "concrete/rebar/steel" whatever-the-f*ck, with materials I can buy at Home Depot for under $300, why don't you just admit you're terrible at your job, call a Mulligan, and instead tell the Democrats you want the money for the care of our Veterans, the elderly, education, or healthcare. Because the Democrats would actually say yes! Or shit, invest that money in that company who made that Tupac hologram at Coachella so I can finally get that David Bowie-Michael Jackson-Prince concert I've always wanted.
That last one was a selfish request I know, but I assure you Mr. Trump, unlike your wall, THAT would actually pay for itself.