For Yu Darvish, we know he can either sign with the Rangers, or go back to Japan. Prince Fielder is a very different matter though.
So, we have two different contests. First is the Yu Darvish contract, assuming he signs, length and dollar amount. Second, is who, how long, and how much. I'm sure we can come up with a decent prize if need be, but until we figure that out, let's use this thread to put in some guesses shall we?
I'll start the bidding with Darvish: 5/$78, Prince goes to the Nationals at 8/$175
UPDATE 12/23/2011: The current averages... Darvish, 5 years, $68.45 million. Prince, Rangers, 6 years, $145.6 million.