Randall Burns has pointed out that a Green Card is worth six figures on the Indian dowry market, and citizenship is worth more.
If I had to pick a number, I'd say citizenship is worth a round million dollars, because I recall that, years ago, a poll was taken in which American citizens were asked if they'd give up their citizenship for a million dollars. Almost all said no, and that was only because there wasn't a space in the form for "Hell, no!"
So that's what the Axis of Amnesty is proposing to give a away to every illegal immigrant—a check for a million dollars, payable to them, drawn on you. The price tag? Maybe $5,000, paid in installment.