Best to just make potions in Dragon Age: Origin. I think the elves stock unlimited herbs need for them, and the city stocks the other materials, so if you run back and forth you can make a bunch. I made like 60 health potions and it kind of broke the game for me.
I much prefer "Drakensang's" method where there are only enough materials available in the world to craft like 20 health potions total (and that's after like 2 hours straight of searching for herbs on the the different maps), so you have to ration them for only the big boss fights.
In fact, now that I think about, I actually think I prefer Drakensang: River of Time as a whole to Dragon Age. While Drakensang's story isn't as good, it's a much better balanced game all around. In Origins Mages were too powerful.