I would guess it wouldn't be much, probably a little north of 1 million, but hell, any little bit can help.
Also, someone mentioned Chris Polk. As a USC fan watching a lot of Pac-12 games, I don't like Polk too much. He was really impressive as a freshman but fell off as his career at Washington went on. It seems like his work ethic sucks, as IIRC his combine numbers weren't too good. The Bears need to be looking at a power back, similar to Barber, in rounds 3 or 4, like a lot of members here have pointed out. Vik Ballard from Mississippi State and Ryan Turbin from Utah State come to mind for me.