Cheapest to most expensive crafts?
All the crafts are inexpensive and about the same price to level if you get your character to level 80 first. Level 80 drops enough money to easily do any craft.
If you do not count your time running around doing hearts for the karma vendors cooking has to be the cheapest for about 1 gold. Jewels are a bit of a pain, but still very easily completed for less then 5g. As long as you are crafting for the highest level discoveries you can it is not going to break your bank at level 80.
Artificer is the cheapest at 2 – 3g and no karma cost.
80 Guardian. 80 Warrior. 80 Thief. 80 Engineer. 80 Necromancer. 80 Ranger.