All of a Latin America is responisible for funneling over 22 billion dollars a year from the US. Mexico is the chief culprit of this leeching behavior.
In which case, we don't need to compel them to write any checks to get reimbursement for the wall. Trump has already brought up the possibility of ceasing remittances and limiting--if not stopping outright--the export of dollars out of the US to Mexico.
I believe you're talking only about trade. And I don't question what you say regarding that. In the past, Mexico and other nations would pay a tariff to export to sell in the U.S.
Having Mexico pay to build a wall would essentially be a small tariff (relative to Mexico's net profit) in order to continue to do business in the U.S.
But something you didn't mention is: the two largest sources of revenue in Mexico are 1) the Mexican oil industry, and 2) wire transfers by Mexicans in the U.S. to family members in Mexico. A shutdown of those two streams of income would bring Mexico to its knees very quickly.
