Now, in reality that economic analysis looks only at a small portion of the costs. Essentially what they are looking at is increases in entitlement spending. The problems include that they aren't looking at factors including:
Increases in crime and disease following looser border control.
Costs of decreasing wages to an already strapped American working class.
That $127 Billion estimate is very much a best-case scenario. NSF and my own previous analysis put the estimated costs at closer to $100K/illegal immigrant-which might mean the $127 Billion estatimate is more than an order of magnitude off.