I might be one of the few people who plays the "Crafting" game 90% of the time while in this game
( since I've been playing since pre-launch and already leveled 10+ level 50's on both sides )
I've been making about a million credits per week on a constant basis since last summer crafting mid-level (late teens to late 30's) Purple Synthweave and Armormech Armors, Purple Armstech Weapons, Purple Biochem Implants, and Purple Augments from all three crafting skills.
All I craft and sell are Purples (maybe a few blues left over from a RE)
The Level 9 - 15 Purple Armors are mostly bought by Twinks for their toons who are starting PvP, but they don't sell that well and the profit margin is relatively small.
The level 20's - Mid 30's Purple Armors sell the best, and I would usually craft between 5-10 each of Light, Medium and Heavy - Bracers, Belts, Gloves, Boots, Chest, Legs, various weapons and Implants per day, and they usually sell out before they expire on the GTM.
I sell these anywhere between 12k-20k each (not too low and not too high) and the profit margin for these is around 10k-17k each, so that comes to about 200k-300k profit per day.