Sorry, but I don't think chocolate silkies are available in the US right now. You could try finding birds to get the color chocolate, but I have no clue how to point you in the right direction. Try contacting Sonoran Silkies on BYC members list. Sonoran knows a good deal about the chocolate gene.
If you're looking for chocolate, the gene is not available in the US, only the dun gene. I believe there are a few breeders working on choc silkies, but they're not readily available. At this point, your best bet would be to start with some nice typey black silkies and cross with another breed that carries dun, such as oegb, although they'll be a lot to work out typewise.