Keep an eye on eBay. have seen several Blacks and Blues lately and they were exhibition quality. Also the other online auction sites. Hope you locate some. I may try to add Blacks as well this fall. We are adding Whites...if the eggs hatch. I am trusting a Chocolate Muscovy hen with that task.
I'll keep watching but i have been on ebay and featherauction (only 2 i know about in addition to here). I only ever see the occasional decent white, anything colored is either small or pied.