I used to rule the world
Seas would rise when I gave the word
Now in the morning I sleep alone
Sweep the streets that I used to own
-- Coldplay, Viva La Vida
Before this sends anyone off on a wild spending spree, buying up rookie cards, there's some history to be examined. The fifth edition of Gary Engel's Japanese Baseball Card Checklist and Price Guide lists the above Kazuo Matsui 1994 BBM rookie card (#506) with a value of $70. The book was published in 2002, roughly a year and a half before Little Matsui signed with the Mets. I had actually seen the card go for more than that on eBay. This card once ranked among the most valuable "regular" BBM cards out there, along with Ichiro and Hideki Matsui's rookie cards. The latest version of the Checklist and Price Guide (the seventh edition) lists the card at $40. I've seen it (and actually bought one) for MUCH less than that on eBay.
I'm not making any statement on whether or not I think Darvish is serious about asking to be posted or whether or not he'd be successful in the majors. I'm just saying I've seen something like this before and it didn't go the way everyone expected it would.