Well, not playing a Mystic I can't address that, lol. But...
Making money in tradeskills is more about knowing your market than what class you choose. If there were one class that made money better than all the rest, well, we'd all be that class!
Since you're mostly a spell-caster, Sage couldn't hurt. You'll be able to make your own spell upgrades to Adept III (one notch below the dropped and expensive Master I's).
Edit: I hate advising people on a tradeskill class, because if you're into crafting you can barter or earn cash for 'most anything you need.