There are repeatable quests called dailies that can be done once per day (reset at 7 am EST everyday). They give you a decent amount of credits (7k to 14k per quest) and currency called Daily Commendations that can be used to purchase Rakata level implants, earpiece, armoring and hilt/barrel that are of tier 23 epic quality (purple).
The Rakata stuff costs 120 daily commendations and the armoring/hilt/barrel costs 8 daily commendations each.
There are two vendors in the Imperial Market in on the Ilum base that sells these, they are called mission support vendors.
Ilum: To start them, you need to finish your class quest first. Doing so will give you a quest called FIRST STRIKE that ask you to report to the Imperial fleet and this quest will direct you to Ilum for its quest series. The quest series itself is fairly short but the mobs are tougher so be prepared to spend 2-3 hrs to finish them off. Each quest will give you 3 daily commendations and unlock daily missions on Ilum.
Belsavis: Belsavis also have a bonus series that opens up. The entire bonus series will also take 2-3 hrs and will unlock daily missions on Belsavis. Unlike the Ilum series, this bonus series do not reward daily commendations.
Below is a list of all the dailies on Ilum/Belsavis.
Ilum – 8 Daily Commendations
Ilum base
- A Tightened Grip – Lord Tetsu – x1 Commendation
- Defend the Shipment – Major Dermian – x1 Commendation
- Operation Shatterstorm – Operative Che’nash – x1 Commendation
- Poisonous Strategy (Heroic 2+) – G-4T – x3 Commendation
Imperial Waystation
- Rightful Owner – Captain Barstead – x1 Commendation
- Sabotage – Colonel Baramak – x1 Commendation
The reward for the heroic one on Ilum is tier 22 epic (purple) level enhancements or blue class VI prototype box
Belsavis – 17 Daily Commendations
Imperial Domination Outpost
- [Heroic 4+] – Lights Out – Corporal Haddon – 3x Daily Commendations + orange companion weapons or blue class VI prototype box
- [Heroic 4+] – Old Enemies – Lord Shaar – 3x Daily Commendations + purple tier 22 armoring or blue class VI prototype box
- Invisible Threat – N4-71- 1x Daily Commendations
- Unintended Consequences – Major Charkron – 1x Daily Commendation
Deep Launchpoint Transporter
- Reluctant Volunteers – Darth Synar – 1x Daily Commendation
- Ancient Transmissions – AR-72 – 1x Daily Commendation
- Found in Translation – Specialist Nattis – 1x Daily Commendation
Signal Monitoring Center
- Droid Malfunction – SD-9 – 1x Daily Commendation
- [Heroic 2+] Freeing the Fallen – 3x Daily Commendations + purple tier 22 mods or blue class VI prototype box
- The Carriers of Xenovirus Prime – 1x Daily Commendation
Tunnel north of Signal Monitoring Center
- Deadly Mutations – 1x Daily Commendation
Rewards for Heroic ones
In total you get 25 daily commendations per day. Each ear/implant costs 120 so you will need about 5 days per piece (getting the first piece will be faster due to the extra daily commendations from the Ilum series).
Checklist for the dailies mentioned above here