Thanks to Cliff C. at Bronx Banter, we have some stats to compare the recent acquisitions of two Japanese pitchers in the AL East:

             Igawa   Matsuzaka   Delta %
ERA           3.15        2.95     M +7%
K/9           8.49        8.70     M +2%
BB/9          2.86        3.23    I +13%
K/BB          2.97        2.70    I +10%
HR/9          0.84        0.72    M +17%
H/9           8.31        7.07    M +18%
WHIP          1.24        1.14     I +9%
Interesting. The average differential between these two pitchers across all seven categories is just shy of 11%. Now take the total price for each pitcher, and then amortize the posting fee over the life of the contract for the "all-in" price:
Total          46m        103m   M +124%
All-in/year   9.2m       17.3m    M +88%
Is it always true that the value of something equals the price that you paid for it?