Champion Gear Bag (Unique)

Cost
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200x Mercenary Commendation (http://www.torhead.com/item/5i5fkvm)
200x Warzone Commendation (http://www.torhead.com/item/7RcvnS0)

If you only have Warzone commendations you can trade them at a rate of 30 Warzone for 10 Mercenary which comes to a total of
800x Warzone Commendations (600x Warzone to trade for Mercenary plus 200x Warzone for the bag price)

Contents
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3x Centurion Commendation (http://www.torhead.com/item/2eRE78r)
OR
1x Centurion Commendation (http://www.torhead.com/item/2eRE78r)
1x Unassembled Champion token (http://www.torhead.com/search/Unassembled%20Champion) which are used to buy any type of gear (Light/Med/Heavy or Weapons) corresponding to the slot the token is for

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Puntr
Sith Assassin
Bondar Crystal
http://www.twitch.tv/puntr

The first post is a great explanation of how to obtain this bag, but there are more ways to help you obtain that Champion gear faster. Specifically, Daily / Weekly Missions!

Don't pass up grabbing theses missions because the rewards are well worth your time. Time that you will be spending in Warzone battle already while getting your 800 Warzone Commendations. The Daily Mission simply requires 3 wins in Warzone battles. The Weekly Mission requires 9 wins.

Rewards: Daily will give you an option of choosing between a Champion Gear bag or a Battle Master Gear bag. ** The Battle Master Gear bag requires Valor Rank of 60 to open it **
Weekly will give you 2 Champion Gear bags AND the option of choosing between Champion / Battle Master for a 3rd bag.

As an added note the PvP Daily / Weekly for Ilum reward the same as above. These are easy to do and great chances for Champion gear that is well worth the effort and time.

P.S. - What do you do with those crappy Centurion Commendations? Well.... I buy gear for my companions :)

Good Luck!

You can receive this bag from a number of different methods.

You can buy it for 200x Warzone Commendations & 200x Mercenary Commendations ( 800 Warzone commendations as it takes 600x Warzone Commendations to get 200 Mercenary Commendations)

You can do your daily pvp quests ( Collect 30 Enemy Armaments from Ilum / Win 3 Games of Warzone ) - These 2 quests will give you 1 Champion Gear Bag each

You can complete your weekly pvp quests ( Collect 150 Enemy Armaments from Ilum / Win 9 Games of Warzone ) - These 2 quests will give you 3 Champion Gear Bags each

Also, if you have Valor Rank 60, You can choose to take a Battlemaster's Gear Bag instead of a Champion gear bag from your dailies. This only happens with DAILIES and not WEEKLY's. You will always receive 3 Champion Gear Bag's for your weekly's unless BioWare change it.

Be prepared to open a whole bunch of these.
So far at level 50 I have opened about 15, each one gives 15 Centurion commendations and 7 Champion commendations (as already said in the comments), so far I have recieved one unassembled item which was a relic, (the cheapest piece) lol.

Important tip: Make sure you aren't too eager about getting gear, if you feel it helping you earn medals in WZ's and whatnot, then get some. But, if you end up buying an expensive champion part, you might get it as an unassembled the next bag (which would make those x amount of champion commendations you spent a waste). Therefore I suggest that you start with buying items you can have 2 of (Relics, Implants).

If you are a class that can play several roles, like I am (Scoundrel), this will not be that big of a worry since you will probably be getting several gear sets for different specs. Just keep it in mind.

EDIT - opened another 9 bags today, no luck.

EDIT 2 - 30th bag, still nothing except for the one relic.