From draftexpress, here's a list of players who earned between $8.5M and $10M last year:
Salmons, Landry, Kidd, Stuckey, Mo Williams, Scola, Odom, Beidrins, Diaw, Devin Harris, Bargnani, Stephen Jackson, Richard Jefferson, Gerald Wallace and Calderon.
Like it or not, but all of those players were given those contracts by teams other than the Celtics. Pretty tough group, but who's going to look at that list of players and then say that there's no way another nba team would offer Jeff Green similar money? Who's going to say that Green's too far below that level of player to get a similar offer, or even multiple offers?