have a look here, these are your missing mounts
Do you have any Horde friends? If you do, let them take over Halaa (for the graveyard) and just farm then at the graveyard. Mind you, those mounts need lots of dusts from mobs in Nagrand, but it's free.
Or you can farm Rivendare's Deathcharger (piece of cake to do but again, RNG) and take up Archaeology. The skeletal raptor mount pops without fail once you reach a certain skill level.