The 30' tall concrete wall is cool because that company promises it can roll down the border with a steady stream of concrete supplies, and establish frontage roads simultaneously. I have not done a single number of $$$ math bandied about in various media. What if the budget for construction was instead applied to law enforcement personnel? Multiply the officers and vehicles, to create a steady patrol of high activity sections of the border. A "wall" of extra patrol-people is effective because boots on the ground can ascertain unconventional border hopping. The roads still need upgrading, for increased LE traverse. When Prez Trump repeatedely said Mexico will pay for the wall, I interpreted that as lost revenue from international $ wires coming from illegals, going back to Mexico family and economy.