Colour crystals don't sell very well, I'm afraid. It's the gemstones that are sought-after, and they're acquired through Treasure Hunting.
But synthweaving can work, too. Some of the nicer-looking orange gear is Lower-level, and is very cheap to make. You can easily sell them 9-19k apiece, depending on demand\supply ratio. Just make sure you find the schematics.
Low-level colour crystals sell extremely well, as do enhancements. PVPers love twinking out their characters. You can make money on lv50 crystals, but not by crafting. (Hint: there are idiots out there who list crystals on GTN for far less than it costs to make them...) You can RE hilts at end-game. Artifice is not a bad choice at all for a force-using class. Oh, and Treasure Hunting can definitely be a money-maker.
The markup on low-level synthweaving stuff is good. Belts and bracers also sell well. I'd never take synthweaving or armormech as a moneymaker though, getting the schematics is time-consuming and expensive. I like to collect them, but the money I make simply subsidises my desire to play dress-up.
My advice to anyone rolling a new character though? Take 3 gathering skills, at least until you get to lv35 or so. You can easily and quickly level up mission and crafting skills when you have 3 or 4 companions, and I've never had difficulty equipping a character with the money and comms I make from questing. My personal choice as a money-maker? Archaeology, slicing and scavenging. If you're going Biochem at end-game you may want to switch slicing or scavenging out for Bioanalysis. Don't switch out archaeology unless and until you're taking your crafting skill, it's your real money-maker as far as gathering skills go.