Donald Trump plans to deport all 11 million undocumented immigrants out of the U.S. and build an “impenetrable, physical, tall, powerful, beautiful, Southern border wall” to help “make America great again,” as his campaign slogan goes.But some experts say those measures would come at a tremendous cost and would require a very tricky political dance to get them enacted, if Trump were elected.“The actual process of finding and removing undocumented immigrants is not as simple as simply purchasing them a bus ticket and sending them across the border to Mexico,” said Ben Gitis, director of labor market policy at the American Action Forum, a conservative-leaning think tank. He estimates the deportation process would cost $300 billion, and the fallout could mean another $600 billion loss to the economy.This would be an unprecedented undertaking, and cost estimates vary widely. A Washington Post report said it would cost $35.6 billion at the bare minimum to enact three specific parts of Trump’s policies.So with the final presidential debate Wednesday night promising a discussion of immigration policy (among other topics), here’s a look at what the GOP nominee’s immigration plans could mean if he pulled them off as president.