Late in Wrath, you could purchase Commendation Badges for five of the neutral factions with rep rewards with Emblems of Triumph. These Commendation Badges were introduced to help gear up alts, and they were a godsend for getting shoulder and helm enchants.
These commendations are:
Argent Crusade Commendation Badge
Ebon Blade Commendation Badge
Kirin Tor Commendation Badge
Sons of Hodir Commendation Badge
Wyrmrest Commendation Badge
Each one of these grants 520 reputation for the appropriate faction, up from the original 250. Humans get 10% more, so 572 for Diplomacy. (Pilgrim’s Bounty has a buff which can give you an additional 10%. Yes, it stacks with Diplomacy.)
When these Commendations were available for Emblems of Triumph, they were only available by running Northrend dungeons. But since the Emblem system was removed and replaced with Justice Points, these are now cheap.
How cheap? Each Commendation is 16 Justice Points.
That’s dirt cheap.
Neutral to Exalted for any faction is 42,000 reputation points:
Neutral to Friendly: 3,000
Friendly to Honored: 6,000
Honored to Revered: 12,000
Revered to Exalted: 21,000
Since each Commendation rewards 520, you’ll need 81 of ‘em, which will in turn cost you 1296 Justice Points.