I'm an estimator/engineer for a construction company. I have no clue what each wall section costs, nor their length so I'll assume $12k per 30 lf. Includes material & labor:
2000 miles = 10,560,000 ft of needed wall.
/ 30 lf each section = 352,000 total sections.
@ $12,000 per section = $4.2 billion
Not counting existing sections of wall, and places where no wall is needed/planned… me thinks the $5 bb POTUS wanted was just his trademark way of asking for more, to 'settle' on the actual desired amount.
Anons feel free to dissect me.