Black Copper Marans(the darkest layers available) were just too hard to get hold of.
From what I have been told, the darker the egg, the poorer the layer. It takes time to put on all that pigment, so the more darker the egg, ie the more pigment required to get that dark coloration, the longer the egg must stay in the chicken.
Its true - the feed stores never seem to get them in. Last year I ordered hatching eggs off eBay. I won an auction for 8+ eggs and the seller sent 11. Only one hatched but count my lucky stars, it was a pullet. I would have to say she is a decent layer - not like the production varieties for sure, but she tends to lay eggs 3 days in a row, take a day off and continue in that cycle. So I get 5-6 a week from her which I don't consider bad at all. She started laying around October, and then took the whole month of January and half of Feb off. I was a little peeved that a new laying pullet was taking a break so soon, I have to admit. But since she started back up again a couple of weeks ago, she has gone back to her consistent 3 on, 1 off cycle, so I really can't complain.