Citizenship: For Sale By Owner

What do you think of this idea? Dwight R. Lee, at TCS Daily, is suggesting that poorer citizens should be able to sell their most valuable asset--their U.S. citizenship--on the free market (with a system in place to screen potential purchasers, of course, for terrorists and other threats.) He says that its going rate would be high, high enough to allow those impoverished citizens who so desire to live much more comfortably in another country, where the cost of living isn't so high, while bringing motivated and productive people here to the States to replace them. He offers this as a way to help the homeless and panhandlers in America, and also those foreigners eager to become legal working participants in the American way of life. While I understand the reasoning, I'm not so sure I can mentally go, with any comfort, where Lee is taking things. Citizenship as a commodity... Any opinions?