We didn't pay to import them... we shouldn't have to pay to export them. The federal and state governments should create an environment toxic to illegal immigrants. No housing, no jobs, no benefits. If you are here illegally, you are persona non grata. You do not exist. If you are a government employee or private citizen that decides to break these laws, you should lose your business license, property, and freedom.
It should not cost the gummint a single dime to enforce these policies.
The apologists like to throw up their hands and scream, "You can't physically deport 13 million illegals! It's impossible!" And they may have a point.
But where they pop up -- in traffic stops, in routine investigations, in attempts to use forged ID, there should be no doubt that we can and should bill the government from which the bastards came for their processing, food, shelter, clothing, and delousing, along with their travel costs back to their home country. And if the country doesn't want to pay, we freeze their assets until they do.
As long as they stay under the radar, they are persona non grata. They can't get a bank account, they can't collect benefits, they can't get a job. Remove the impetus to be in this country and the bastards go away. It's real simple.