If you have some time on your hands, the "cheap" way seems to be effective: I hunt Miasma with my sampire and loot everything until i'm almost overweight then go home and drop the bag - repeat three times, end up with 150 items or so - then start training with the would-be artificer.
The system is very simple: I check every single object, imbue if I can have a 60/62% chance by using a single residue and gem, unravel if the chance is too low. When the chance is too high, I'll see if I can lower it with a single gem on a different property (say, adding some LRC), otherwise unravel.
For the sake of argument, here's the numbers for my last session:
Start 16:16 - end 16:47
Skill 71.6 -> 75.1
Residue 165 -> 6
amber 2234 -> 2195
citrine 2143 -> 1878
All in all, to gain 4.5 skill I used 159 residue and 304 gems. Roughly it's about 340gp for a .1 - which means, if the gains remain like this, that you can train all the way from 40 to 120 spending less than 300K gp and in less than a couple days. Not that bad, I think.