http://www.becker-posner-blog.com/2005/02/sell-the-right-to-immigrate-becker.html
Very interesting idea. Basically proposes to end the immigration lottery system and allow the free market to dictate how much someone will pay for US citizenship (assuming something doesn't disqualify them). This could be accomplished with some sort of loan program, and in a follow-on he also mentioned you could have a like a 3-yr trial period for that person to decide if the fee is worth it to stay here.
Makes a lot of sense on the surface. But he may be grossly overestimating the transitive value of skills - the call-center worker in India who comes here doesn't get an equivalent job making 5X what he did in India, his job goes to someone else in India and he then throws his lot in with the pool of unemployed here...for $50k. On the other hand, if you're an entrepreneur that can generate some real economic value you can go to the front of the line.
The Dems will never stand for forcing their new votes to pay-to-play.