Feds estimate over 1 million will apply for Obama's amnesty, will cost millions
From this :
The Obama administration’s new plan to grant temporary work permits to many young, illegal immigrants who otherwise could be deported may cost the government more than $585 million [important: see below] and require hiring hundreds of new federal employees to process more than 1 million anticipated requests, according to internal documents obtained by The Associated Press.
...U.S. Citizenship and Immigration Services estimated it could receive more than 1 million applications during the first year of the program, or more than 3,000 per day. It would cost the government between $467 million and $585 million to process applications in the first two years of the program, with revenues from fees paid by immigrants estimated at $484 million, according to the plans.
The government estimated that as many as 890,000 immigrants in the first year would be immediately eligible to avoid deportation. The remaining 151,000 immigrants would likely be rejected as ineligible.
The plans estimated that the Homeland Security Department could need to hire more than 1,400 full-time employees, as well as contractors, to process the applications. Salaries were included in the agency’s estimates of total program costs...
The total cost wouldn't be in the $585 million neighborhood; much of that would be offset by the fees received and it would depend on how many illegal aliens get waivers . In any case, in federal terms, hundreds of millions isn't that much. Harping on the cost would be ineffective because illegal immigration supporters will a) point out that much of it will be offset by fees, and b) try to claim that the fiscal benefits outweigh the costs. 
A better way to oppose this program is to point out that the Feds themselves admit they'd be adding almost a million legal workers to the job market while millions of Americans are unemployed.
For more, see:
* DREAM Act describes that anti-American bill and has past coverage of Obama's amnesty
* immigration wage floor describes how legalizing illegal aliens will impact lower-skilled American workers
* the post discussing how most of those negatively impacted by Obama's amnesty will be Democrats
* Obama immigration for extensive past coverage of his actions on these issues.
 The article is by Alicia Caldwell.
Homeland Security Secretary Janet Napolitano told Congress last week that the government would grant waivers "in very deserving cases."
 There is one situation in which harping on the cost could be extremely effective: if doing so could play a role in a winning lawsuit designed to block the program. One possible way to block the program might be due to Obama deciding by executive fiat to spend money without Congress' approval.