First Aid 1-375 is $34.35, or $26.09 for 300-375.
It is a secondary skill, so it costs you nothing. First Aid does not take one of your two profession slots — every character can have it alongside mining, tailoring or anything else. That is why every raider has it and why it is the cheapest self-sufficiency upgrade in the game.
Heavy Netherweave Bandage is the point. At 375 you can bandage yourself for a large heal out of combat with no cooldown and no consumable cost beyond cloth — between pulls, after a wipe, on a corpse run. For a casual player who is not running with a healer, it is the difference between chain-questing and sitting down to drink every mob.
The progression is short: Heavy Runecloth Bandage to about 330, Netherweave Bandage at 330, Heavy Netherweave Bandage at 350 and that carries you to the 375 cap. Roughly 100-150 Netherweave Cloth for the whole Outland half — which is why this is the fastest profession on the site.
Master First Aid comes from a book, not a trainer. Master First Aid - Doctor in the House costs 5 gold and needs 300 skill: Burko at the Temple of Telhamat for Alliance, Aresella at Falcon Watch for Horde, both in Hellfire Peninsula. Rival pages send you to a trainer who cannot teach it.
Triage is optional now. The old Doctor Gustaf VanHowzen and Doctor Gregory Victor quest was the Classic Artisan step; it is flavour in TBC, not a requirement.
