My wife hates the sound of the mechanical keyboard but I absolutely love it!
http://www.amazon.com/Razer-Blackwidow-Ultimate-Mechanical-RZ03-00381900-R3U1/dp/B008U5ZNIG
^This
I make millions of credits per week through synthweaving and armortech just selling augment kits. Throw in the 27 armorings, mods, and enhancements and its probably closer to 15/20 million.
You could start there but it's not gonna sell. It's a low-level crystal that is easily surpassed by the new +41 lvl 10 crystals. Sure the color is cool, but it's probably too late to make very much off it.
The 30% is dependent on class, role, etc. You should really go to the class forum and do some reading. Mmo-mechanics has some great info too. Just stay away from noxxic.com. That's where bads come from.
You can get more than 13k per week if you use the purple trophy when right below 12k. This will put you above 26k in 2 weeks. See the breakdown on Dulfy's site.
http://dulfy.net/2013/02/12/swtor-relics-of-the-gree-event-guide/