I would go with egg color over bird color if you want to sell eggs. I would give some leeway on bird color unless it was a non-recognized color or a sport (unless you REALLY LIKED that sport, but I wouldn't breed it or try to sell the eggs except for eating.)
Were you planning to sell eggs for hatching, or for eating? If for eating, the birds can be purple and plaid and the eggs will taste the same. If you want people to pay a lot for your eggs, the birds must be large, well feathered, proper color, good dispositions, proven lines of dark producing eggs, without known traits like slow feathering, excessive white, combs with too many points, extra comb growths toward the back that look deormed, straigt toes, proper leg and beak color, all that. It get's complicated and it is hard to find the ideal combination that will go on to reproduce themselves and continue to have dark eggs. That is why some lines are more expensive, and I would suggest getting the most proven lines you can. Sometimes you can get them one generation removed from the well known breeders like Bev Davis, bayhorsebonne, and pay somewhat less and avoid year long waiting lists or very high prices. That is just my .02 worth.
