I'm not a great wall fan myself. New Hampshire is about as far away from the Mexican border as you can get. But ABC was just claiming that the border wall would cost $25 billion. Which is rediculous.
The US Mexican border is 2000 miles long. At 5280 feet to the mile, that comes out to 10 million feet in round numbers. Chain link fence material, the chain link, fence posts, ties, and everything is about $5 a foot. I looked it up on the internet. Let's assume installation is about the same as the cost of materials, so make it $10 a foot, or $100 million to do the whole border. That's a far cry from ABC's $25 billion.
Actually, there is a bit more to doing it right. To prevent people from digging under it, we ought to put a solid concrete footing under the fence, all the way across. That might cost another $100 million. Then we need an access road on our side of the fence to allow the border patrol to get men to the site of an illegal crossing in a hurry. It can be a dirt road, just good enough for a jeep. And we ought to fly air patrols in Cessnas (not $1 millon UAVs) daily. The real purpose of the fence is to stop vehicles from crossing, or at least to leave an unmistakable hole where someone crashes thru. You need air patrols to spot the big holes in time to get the border patrol in pursuit of the fence crasher before he gets away.
Even with all this stuff I'm thinking we could do the wall for less than $1 billion.