I have a very good friend who bought blue marans hatching eggs from the seller on eBay with the initials of Recreational Vehicle this past spring - she had a good hatch, but I believe got one blue and one splash...the rest were sport, and a cuckoo. Interesting...
There are many really good lines; I'd suggest joining this forum if you are serious about the breed:
http://groups.yahoo.com/group/Marans_Chicken_Club/
On the forum, there is a database of folks selling specific breeds (hatching eggs/birds), and folks LOOKING for specific breeds.
Any...