Amazon.com offers a black iDog from Hasbro for pre-order. This one will fit perfectly to your Sony PSP.
The black iDog (or i-Dog) will ship January 1st 2006, which is a bit to late to put it under the Christmas tree.
The classic white iDog sells for $24.99 on Amazon.com, but is currently sold out.
The black iDog is available for pre-order at also $24.99.
The pink iDog, which is only available in Japan, is exported by AudioCubes. They also sell the blue iDog internationally.