There was a total revamp of Alchemy in Winter of 2006 when PoR came out. Alchemy is now much more friendly to makers of potions & their customers.
First: Shamans can get to roughly 230 with just vendor purchased ingredients. Beyond that, you need farmed or foraged items.
Virtually all components are sold in Abysmal Sea, Freeport, Plane of Knowledge, Shadowhaven, & I think Crescent Reach (don't have it to verify).
Second: the potion names explain what they are. Learn them if you buy potions in the bazaar.
===Distillates--the buff/heal potions you buy in POK as well as buff effects like damage shield, regeneration, mana pool boost, and cure poison/disease.
===Essences--illusion potions
===Mists--group buffs like SoW, invis, lev, & EB
===Philters--catch all category including gates, effects like SoW, EB, see invis, lev, shrink, grow, ivu, cannibalize, etc. Buff effects that are helpful but don't make you more powerful, per se (those are distillates).
===Effusions--resist buffs
===elixirs--stat buffs. They can also increase your stat cap somewhat.
===tonic--focus effects for spell casters
===suspensions--thrown bottles with an effect if they hit, like a DD, slow, snare, or stun. Not very effective at higher levels atm. =(
Third
The suspensions may require special bottles/vials in the recipe, which are made via pottery.
Fourth
Many individual potions have either 5 or 10 types, based on their required level & their strength. For instance, Philter of the Wolf I increases run speed by 35% & costs under 1pp to make, while PotWolf V increases run speed by 55% & costs around 7pp to make. "Speed is a function of money, how fast do you want to go?"--old saying in hot rodding cars.
Another popular potion is DS pots--Distillate of Skinspikes I is a 10 hp damage shield that lasts about 7 minutes & costs about 1pp to make. Skinspikes x is a 55 hp DS that lasts about 15 minutes, required level of 65, & requires a drop from level 60+ zones in PoR.
Based on cost & availability, you might want to stick to the level 5/6 potions, since they can be made with vendor stocked items. Any required drops will increase the rarity & thus the price significantly, more than the added cost is worth.
Speaking of cost, you know those heal/haste/clarity potions you buy in PoK & swill down like coffee at a board meeting? Well, shamans can make them for about 1/4th of the cost you buy them. Check the guild shamans & also the bazaar for discounted potions. If you are level 65+, save any Nodding Blue Lillies you come across, because that is the drop necessary to make all the type X potions.
I hope this helps everyone. Please buy more cool potions from my shaman in the bazaar! 
Wulf
