Thought I would make my first post a bit of a contribution to an already great guide. I’m a rogue who just hit 58 who is also a herb/alch 300.
Mountain Silversage is, in my experience, the most beneficial herb to farm for profit. It’s used in Elixer of the Mongoose (+25agil and +2% to crit/1hr) as well as Major Healing potions (The highest healing potion available) and Greater Arcane elixirs (+35 to spell damage/1hr). Prices on your server may vary but on mine it’s almost always more than 1G per, even in large stacks. The potions sell well also.
There aren’t many place to find it in abundance, but in my experience the best places to farm are the afore mentioned Un’Goro crater. Run around the edges and then hit up the mountain in the middle for a couple of more possible spawn points.
Winterspring. It’s a big zone with lots of spawn points for Mtn. Silversage. Just keep to the mountains and run around the zone on your mount and you’ll find a bunch.. get lucky and you won’t even have to fight anything for most of them. Watch out in the NW for high level (58+) stealthed frostsabers though. It’s also the only place to get Icecap.
Northern Felwood, north of Bloodvenom falls. Again, just mount up and hug the mountains. Not my favorite place to farm as it seems to be a popular spot for herb farmers on my server. Plus the zone is small and crowded with mobs as well.
E. Plaguelands. Griffon into Lights Hope Chapel and run along the mountains from Tyr’s Hand to Noxious Glade for a few spawn points and then along the south of Plaguewood for a couple of more. Couple of mobs Just north of LHC in front of Noxious Glade, but most of the gathering here can be done without fighting as well, with a little manouvering.
Burning Steppes. Dreadmaul Rock. A great place to grind out your last couple of levels if you are a good solo class. Some quests here as well. Ogres are nice and squishy and there are about 4-6 spawn points on the mountain for Silversage, so it’s a nice place to settle in for some Exp and herbs.
Hope this helps.