Even in an inflated market, I find it hard to believe Duffy ever goes for more than 10m
He has a similar path to Michael Keane in several ways. Didn't get much game time at big club, loaned out lots, left at 21 and found a starting place to develop further down the food chain. Both are more typical old school defenders.
I'd say £20m+ would be needed to make Brighton even entertain the idea. I'd rather have Dunk and Duffy than any pairing of our centre backs currently.