While I don't know what Rick Hahn has in mind as an asking price for Sale, I do believe that Pomeranz. Shaw, Hembree and Owens add nothingto this trade, let alone justify acquiring Robertson as well.
One thing to keep in mind with Sale. I agree he is terrific, but why is he really available? The White Sox have an excellent young core of talented players including Sale, Quintana, Abreu, Eaton, Rodon, etc. Why blow it up? Is it because Sale revealed himself to be a super-whiny prima donna the team found simply too insufferable? Think about his season - blowing up at management publicly over the Adam LaRoche situation, destroying throwback jerseys, etc. The entire fire sale might be based on this guy being a huge headache.