An Arizona senator or something was on TV. She said something approximately like this: "Illegal immigration is costing us a billion dollars a year. That's how much it costs just to keep it at the level it is now."

I'm pretty sure what she means by that is "Trying to stop illegal immigration is costing us a billion dollars a year."

My question on this subject is this: would it, in fact, be more cost effective to simply stop spending that much? Maybe only spend ten million, so you can still keep out the low hanging fruit of illegal immigration. Would the illegal immigrants who would become able to slip in because of this lower expenditure really cost (or cause damage to the value of) 990 million dollars a year?