Mexico won't pay for the wall and the way he proposes to make them pay is foolish and would cause an even bigger influx of illegals.It would not be outrageous. In fact - it would cost pennies compared to the annual burden/cost illegal immigration has on our country - which is estimated to be well over 100 billion dollars annually. Compare that to the 8 -10 billion dollars the wall will cost us - and I'd say that was a sound investment if ever there was one.
This isn't to mention Trump plans to make Mexico pay the wall anyway.
I have read building the wall would be on the scale of building the Eerie Channel. They have the Colorado and Rio Grande rivers to build over and around. There are Indian reservations and private property that have to be considered. It is a construction nightmare.