There used to be a way to buy the Nebula for Marks/emblems. What happened to that? It seems to have been pulled. I was after the ship for one of my characters, so buying it account wide made no sense, and I've been slowly grinding up to the point where I could buy it.
I think I'm almost there, and I went to check, and the option seems to have been removed. Is it due to the sale?
If you do the B'tran explore and the vice admiral B'tran you will get 5 marks and 4 emblems per run. If you do the Breen/Devidian dailies on top of that, you will get another 6 emblems for a total of 15 marks every day after you convert them all to marks of exploration.
So at 200 marks, it shouldn't take long to get the nebula class. You can buy it from ESD.