The Dominique Club of America focuses on the Dominique breed and coordianates shows for the club. A breeder’s directory is also available to members. The club maintains a nice website that also contains a number of contacts.
The Livestock Conservancy (formerly The American Livestock Breeds Conservancy) is a good place to start. They monitor conservation efforts and maintain contacts for a number of livestock species.
Cackle Hatchery in Missouri sells both Dominique large fowl and bantams. Their bantam flock was created from the Unbeatable Beauty line.
Murray McMurray in Iowa sells large fowl Dominique chicks.
Also feel free to check out the two Facebook groups. One is for anyone interested in Dominiques the other is limited to posting by Dominique Club of America members only.
You will notice I have not listed myself as a contact. As you may have seen on the “Who Are We” page I have been out of Dominiques for awhile and am not the best contact for locating stock.