If you find one for sale, be sure to ask if it is 100% Cochin. Some are working on them, but they are crossing Cochins with Wyandottes, Rhode Island Reds, etc.
there is not any way that I know of to get blr from pure cochins. I am working on blr and just had the F2's hatch today. the F1's were blr in color but needed better foot feathering and a single comb and of course type. These F2's have nice feet and about 50% now have the single comb. It's a matter of waiting to see the color now