Currently the option of returning 5 artifact fragments to summon Fangraal, the alliance boss, is incorrectly giving 125 rep (should be 25).
So you only need approximately 1500 artifact fragments to get exalted.
(Each full container run in Ashran gives about 800 fragments, Artifact Fragment - Currency - World of Warcraft)
If you have returning 1000 fragments, wait until fangraal dies so that you can start returning again.
Note that it does not work for the Horde side.