Mercenary Commendation

Located at the PVP world area on Tatooine called the Outlaws Den - Each Security Chest contains 20 commendations and between 2k - 3k credits.
Commendations stack to 1000. Mercenary Commendations can also be obtained by trading in Warzone Commendations. You receive 10 Mercenary Commendations for 30 Warzone Commendations. For 200 of each type of Commendation (Mercenary and Warzone) you can buy a Champion gear bag. http://www.torhead.com/item/eMw3Nj9/champion-gear-bag-unique

Located at
-163, -1124 Near the Market
-365, -916 behind Shifty Panaw
102, -814 behind Blearg's tent
-227, -1347 Next to rock formation between Jo'dath and the market.
30, -1152 Near the dead end path between Jo'dath and Blearg
31, -1096 Near the dead end path between Jo'dath and Blearg.
-287, -898 Inside of hutt near imp enterance.
-343, -1050 Slot in wall in front of Panaw.

Chests are on a long spawn timer I believe. I got a set of chests in the area and didnt see another for about an hour and a half.

-163, -1124 Near the Market
-365, -916 behind Shifty Panaw
102, -814 behind Blearg's tent
-227, -1347 Next to rock formation between Jo'dath and the market.
30, -1152 Near the dead end path between Jo'dath and Blearg
31, -1096 Near the dead end path between Jo'dath and Blearg.
-287, -898 Inside of hutt near imp enterance.
-343, -1050 Slot in wall in front of Panaw.

As of Patch 1.2 Mercenary Commendations have been removed from the game. If you have any left you can trade them for Warzone Commendations at the rate of 10 for 10.

The area Outlaw's Den as mentioned in other posts still has boxes to be found but instead of Mercinary Commendations they contain 20 Warzone Commendations, Credits and a chance to loot Recruit PvP Armor. This Armor is all Level 50 Blue PvP Armor and will be class specific to the player looting the box. Box spawn rates seemed to increase and now it is common to find up to 4 boxes per run. They can be found almost anywhere in the zone and CAN be found inside buildings.

I dinged 50 early and have taken security chests filled with these commendations many times in the PvP area at Tatooine, and I have always been entirely alone at the place.

One spawn point I am 100 % sure of is next to the tent behind the PvP vendor Jo'dath the Exile.