And you're wrong. Late in Clinton's adminstration, the border patrol was deporting about 1.5 million per year. At that time (as best I can find numbers) the budget for the ENTIRE INS was around $4.2 billion.
First off, don't bother replying if you are going to selectively snip, please. It is insulting.
Second, that is indeeed cost prohibitive. Rounding up the ones that are here now and sending em back is money thrown down the drain. Put that money into a border fence and a vastly increased Border Patrol, and take away the aforementioned spigot of benefits that illegals get, and that is a much more effective way to address this.