For me I gain some credits with cybertech, after buying stims, repairs, and some times mats for when I go crazy and start RE'ing 50+ blues to get the epic I want. I'v sold mastercraft ears for 150k and I only put up ship parts and other epic ears for 40k each. Some times it takes a while to sell the ears, and sometimes it doesn't take long at all. Sold some ship parts almost instantly last week.
The link below has the schematics I'v learned. I don't know how much more or less people are making with other tradeskills. But I am okay with how much I have, which usually floats between 1m and 2m credits.
http://s111.photobucket.com/albums/n125/Loyrl/SWTOR