To unlock the rare Yarvok’s Gratitude Badge, you must earn the achievement ‘The Golden Dream’ from the Pirate Incursion Event on Dantooine. To start the achievement, pick up the Quest: [HEROIC 4] Reactor Ransom and enter the phase either by yourself or with a group.

Before initiating combat you will find a friendly droid named R0-BSU aka ‘Robs You’ which offers the option to pay the Heroic Bosses ransom of 15 million credits!
If you pay the ransom instead of playing the Heroic Quest normally, it will immediately complete itself and the player that pays the ransom will progress the achievement. To earn the Yarvoks Gratitude badge and achievement, you must pay the Ransom 10 times aka spend 150 million Credits across the Heroic 10 times!

Once you have payed the Ransom 10 times total on any number of characters, you will be rewarded with a Bound: Yarvok’s Gratitude Badge to your character. You cannot claim extra copies for your ALTs from the achievement window, however the Event Rewards NPC in your factions base will sell you Bound copies of the badge for 1 credit each to any of your characters once the achievement is unlocked.