He doesn't have a plan. He has "concepts of a plan".
Seriously though, I think this article has put more effort into Trump's statements than Trump ever has. It doesn't make his threats any less dangerous though.
Hundreds of billions just to do the deportations, and then there's the cost to the economy:
One study found that Obama's Secure Communities program, which deported nearly half a million undocumented immigrants, not only pulled those immigrants from the workforce but had a ripple effect of decreasing the employment and hourly wages of U.S.-born people as well. Scaling their findings, the researchers estimated that for every 1 million unauthorized workers deported, 88,000 native-born jobs would be lost.
An analysis from the nonpartisan Peterson Institute for International Economics released last month reached similar conclusions. Researchers found that a mass deportation of even just 1.3 million undocumented immigrants would lower GDP and reduce employment in the U.S. by 0.8% by 2028. A larger mass deportation of over 8 million immigrants would have a larger effect, lowering employment to 5.1% below the current baseline.
Undocumented immigrants also paid $59.4 billion in federal taxes and $37.3 billion to state and local taxes, according to a study by the Institute on Taxation and Economic Policy. More than a third of those went to Medicaid, Social Security and unemployment insurance.
Immigration researchers, lawyers, and economists have pointed to immense constitutional, humanitarian and economic problems posed by Trump's oft-repeated pledge. But beyond the anticipated damage to immigrant families, communities and local economies, the roundup and deportation of some 11 million people is near impossible to bankroll, according to an analysis of U.S. budget and immigration court data by CBS News.
TL;DR: Half of American voters are braindead and sociopathic.