One way mentioned previously is faction vendors which could be the cheapest and quickest source depending on who is running the town. A more expensive way is player vendors but they are quick and easy enough to find. A cheap but time consuming way is to work up the npc mage, alchemist, and herbalists at several npc shops by buying them out of the reagents you want every time they respawn (takes about 20 to 30 minutes not sure exactly) If you keep this up after a few rounds the amounts offered will be 999 per reagent (at the normal cost). An even cheaper and more time consuming way is to hunt IDOCs.
