Ballack is entirely in a different class and I were Hoeness at Bayern, I would not let him go at any price, unless of course, it is for Chelsea-style ridiculous amount of transfer income. He is the best German player at this moment, and perhaps will still be in the near future as they are running dry on high quality players.
Owen Hargreaves would be in a position to do better then Biscan and would be a welcome addition to the squad.