It's getting late, but I just wanted to toss in two things:
1) The agency I work with lists prospective couples and their profiles on the website. I don't think I have ever seen an AA couple on it. After asking a few questions (I'm nosey

), I found out that people adopting AA/bi-racial babies through the agency get placements so quickly, most don't even choose to list their profile (and listing doesn't cost anything).
2) I say this from my own experience (and wonder if others have similar) - when I mention possibly adopting an AA child I get numerous statements (from AA and CC alike) about how I need to "respect the heritage", how difficult it would be for an AA child to grow up with CC parents, how I will "never understand the struggle", how I need to teach him/her to "be black", etc. But when I mention adopting from China, Korea, etc, I rarely get comments or "advice", maybe someone telling me about culture camp. Adopting transracially can be a bit scary to undertake, no matter what race you're considering, but to add in all the comments that people make....it can make you second-guess yourself or your ability to provide what a child needs culturally. The comments make it seem like raising an AA child will be WAY more difficult than raising another race (through transracial adoption). Some people are probably scared away by that.....just a guess.