Surprisingly, of the two 2006 Bowman Sterling Prospect autograph cards that I already had, neither of them was the base card. But, now I do have it thanks to the Hochevar Buy-Out.
The base, refractor (#/199), and black (#/25) cards all together as a happy family. And, other than the four printing plates and red refractor (all of which are 1/1 and none of which have I ever encountered), I now own the 2006 Bowman Sterling rainbow. Pretty sweet.